boot: zephyr: MCXN947 currently only does not support swap mode

Update the configuration to remove swap mode support.
MCXN94x ROM Flash API supports writing of 128byes page.

Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>

boot/zephyr/boards/frdm_mcxn947_mcxn947_cpu0_qspi.conf

@@ -2,3 +2,4 @@
 # SPDX-License-Identifier: Apache-2.0
 
 CONFIG_BOOT_MAX_IMG_SECTORS=1024
+CONFIG_BOOT_UPGRADE_ONLY=y