unit-test-app: keep CONFIG_SPIRAM_BANKSWITCH_ENABLE enabled only for psram_8m config

tools/unit-test-app/configs/psram

@@ -1,3 +1,2 @@
 TEST_EXCLUDE_COMPONENTS=libsodium bt app_update driver esp32 spi_flash
 CONFIG_SPIRAM_SUPPORT=y
-CONFIG_SPIRAM_BANKSWITCH_ENABLE=n

tools/unit-test-app/configs/psram_2

@@ -1,3 +1,2 @@
 TEST_COMPONENTS=driver esp32 spi_flash
 CONFIG_SPIRAM_SUPPORT=y
-CONFIG_SPIRAM_BANKSWITCH_ENABLE=n

tools/unit-test-app/sdkconfig.defaults

@@ -27,4 +27,5 @@ CONFIG_SUPPORT_STATIC_ALLOCATION=y
 CONFIG_ESP_TIMER_PROFILING=y
 CONFIG_ADC2_DISABLE_DAC=n
 CONFIG_WARN_WRITE_STRINGS=y
-CONFIG_SPI_MASTER_IN_IRAM=y
+CONFIG_SPI_MASTER_IN_IRAM=y
+CONFIG_SPIRAM_BANKSWITCH_ENABLE=n