[nrf fromlist] tests: secure_storage: psa: its: fix ZMS test

77f19eb made ZMS depend on
FLASH_MAP.
Enable that Kconfig option in the ZMS Kconfig overlay file.

Signed-off-by: Tomi Fontanilles <[email protected]>

Upstream PR #: 94171

(cherry picked from commit 2f40e49)

Author: tomi-font

tests/subsys/secure_storage/psa/its/overlay-store_zms.conf

@@ -1,3 +1,4 @@
 CONFIG_SECURE_STORAGE_ITS_STORE_IMPLEMENTATION_ZMS=y
 CONFIG_ZMS=y
 CONFIG_FLASH=y
+CONFIG_FLASH_MAP=y