Kconfig: Increase default main stack size when CC3XX is enabled

Increase the default main stack size when CC3XX is enabled. This
avoids issues in samples where the default of 1024 would be enough
in upstream, but not in downstream.

Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>

Kconfig.nrf

@@ -11,9 +11,12 @@ menu "Nordic nRF Connect"
 config BOARD_THINGY91_NRF9160NS
 	bool
 
-# nRF Connect SDK needs a larger default stacks for running certain tests.
+# nRF Connect SDK needs a larger default stacks in certain configurations
+#  - For running tests.
+#  - For CC3XX RNG
 config MAIN_STACK_SIZE
 	default 2048 if ZTEST
+	default 2048 if ENTROPY_CC3XX
 
 config ZTEST_STACKSIZE
 	default 2048 if ZTEST