app: boards: fix 9151dk flash page size

9151dk page size defaults to 64kB.
This breaks modem trace to memfault overlay which assumes
255 sectors of 4kB each. Instead, currently we end up with
16 sectors of 64kB, not aligning with partion size 0xFF000.

Signed-off-by: Giacomo Dematteis <giacomo.dematteis@nordicsemi.no>

Author: DematteisGiacomo

app/boards/nrf9151dk_nrf9151_ns.conf

@@ -8,6 +8,7 @@
 CONFIG_SPI=y
 CONFIG_SPI_NOR=y
 CONFIG_SPI_NOR_SFDP_DEVICETREE=y
+CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096
 CONFIG_PM_OVERRIDE_EXTERNAL_DRIVER_CHECK=y
 
 # Location priority order