wear_levelling: clean up Kconfig

components/wear_levelling/Kconfig

@@ -1,45 +1,57 @@
-menu "FAT FS Wear Levelling Settings"
+menu "Wear Levelling"
 
 choice WL_SECTOR_SIZE
-   bool "FAT FS sector size"
-   default WL_SECTOR_SIZE_FAT
+   bool "Wear Levelling library sector size"
+   default WL_SECTOR_SIZE
    help
-       Specify the FAT sector size.
+       Sector size used by wear levelling library.
        You can set default sector size or size that will
        fit to the flash device sector size.
        
-config WL_SECTOR_SIZE_FAT
+       With sector size set to 4096 bytes, wear levelling library is more
+       efficient. However if FAT filesystem is used on top of wear levelling
+       library, it will need more temporary storage: 4096 bytes for each
+       mounted filesystem and 4096 bytes for each opened file.
+       
+       With sector size set to 512 bytes, wear levelling library will perform
+       more operations with flash memory, but less RAM will be used by FAT
+       filesystem library (512 bytes for the filesystem and 512 bytes for each
+       file opened).
+       
+config WL_SECTOR_SIZE_512
    bool "512"
-config WL_SECTOR_SIZE_FLASH
+config WL_SECTOR_SIZE_4096
    bool "4096"
 endchoice
 
 config WL_SECTOR_SIZE
     int
-    default 512 if WL_SECTOR_SIZE_FAT
-    default 4096 if WL_SECTOR_SIZE_FLASH
+    default 512 if WL_SECTOR_SIZE_512
+    default 4096 if WL_SECTOR_SIZE_4096
 
 choice WL_SECTOR_MODE
    bool "Sector store mode"
+   depends on WL_SECTOR_SIZE_512
    default WL_SECTOR_MODE_PERF
    help
-       Specify the mode to store data into the flash.
+       Specify the mode to store data into flash:
+       
+       - In Performance mode a data will be stored to the RAM and then 
+         stored back to the flash. Compared to the Safety mode, this operation is
+         faster, but if power will be lost when erase sector operation is in
+         progress, then the data from complete flash device sector will be lost.
+       
+       - In Safety mode data from complete flash device sector will be read from
+         flash, modified, and then stored back to flash.
+         Compared to the Performance mode, this operation is slower, but if 
+         power is lost during erase sector operation, then the data from full
+         flash device sector will not be lost.
        
 config WL_SECTOR_MODE_PERF
    bool "Perfomance"
-   help
-       In Performance mode a data will be stored to the RAM and then 
-       stored back to the flash. Compare to the Safety mode, this operation
-       faster, but if by the erase sector operation power will be off, the 
-       data from complete flash device sector will be lost.
        
 config WL_SECTOR_MODE_SAFE
    bool "Safety"
-   help
-       In Safety mode a data from complete flash device sector will be stored to the flash and then 
-       stored back to the flash. Compare to the Performance mode, this operation
-       slower, but if by the erase sector operation power will be off, the 
-       data of the full flash device sector will not be lost.
 endchoice
 
 config WL_SECTOR_MODE