zephyr: Enable flash page layout if available

Since not all ICs default to enabling flash page layout, enable it from
the MCUboot Kconfig options whenever it is available.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index d7db75e..4db769e 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -17,6 +17,8 @@
 	default y
         # CPU options
 	select MCUBOOT_DEVICE_CPU_CORTEX_M0 if CPU_CORTEX_M0
+        # Enable flash page layout if available
+	select FLASH_PAGE_LAYOUT if FLASH_HAS_PAGE_LAYOUT
 
 config MCUBOOT_DEVICE_CPU_CORTEX_M0
 	# Hidden selector for Cortex-M0 settings