boards: arm: mps2_an521: some trivial Kconfig fixes

When TRUSTED_EXECUTION_NONSECUCRE is selected, we always
define the default board (mps2_an521). We do not need to
OR with TRUSTED_EXECUTION_SECURE, in this Kconfig
conditional.

In addition to that, we make the BOARD_MPS2_AN521 board
to strictly depend on the corresponding SOC, not on the
SOC series.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

boards/arm/mps2_an521/Kconfig.board

@@ -6,6 +6,6 @@
 
 config BOARD_MPS2_AN521
 	bool "ARM Cortex-M33 SMM on V2M-MPS2 (AN521)"
-	depends on SOC_SERIES_MPS2
+	depends on SOC_MPS2_AN521
 	select QEMU_TARGET
 	select HAS_COVERAGE_SUPPORT

boards/arm/mps2_an521/Kconfig.defconfig

@@ -6,7 +6,7 @@
 
 if BOARD_MPS2_AN521
 
-if TRUSTED_EXECUTION_SECURE || !TRUSTED_EXECUTION_NONSECURE
+if !TRUSTED_EXECUTION_NONSECURE
 
 config BOARD
 	default "mps2_an521"
@@ -18,7 +18,7 @@ if TRUSTED_EXECUTION_NONSECURE
 config BOARD
 	default "mps2_an521_nonsecure"
 
-endif
+endif # !TRUSTED_EXECUTION_NONSECURE
 
 if GPIO