soc: place constant data from rtc_clk.c into DRAM

In release mode, switches in rtc_clk_bbpll_set would be converted to
jump tables. These tables would be placed into .rodata, which caused
rtc_clk_cpu_freq_set to be unusable while cache is disabled. This
manifested itself in crashes when exiting from light sleep:

https://esp32.com/posting.php?mode=reply&f=13&t=3089#pr14590

components/esp32/ld/esp32.common.ld

@@ -117,6 +117,7 @@ SECTIONS
     *(.dram1 .dram1.*)
     *libesp32.a:panic.o(.rodata .rodata.*)
     *libphy.a:(.rodata .rodata.*)
+    *libsoc.a:rtc_clk.o(.rodata .rodata.*)
     *libapp_trace.a:(.rodata .rodata.*)
     *libgcov.a:(.rodata .rodata.*)
     *libheap.a:multi_heap.o(.rodata .rodata.*)