[nrf noup] treewide: Update comment to not mention SPM

fixup! [nrf noup] treewide: add NCS partition manager support

Update comment to not mention the removed SPM secure firmware solution.

Signed-off-by: Joakim Andersson <[email protected]>

Author: joerchan

boot/zephyr/pm.yml

@@ -64,8 +64,8 @@ mcuboot_scratch:
 # Padding placed before image to boot. This reserves space for the MCUboot image header
 # and it ensures that the boot image gets linked with the correct address offset in flash.
 mcuboot_pad:
-    # MCUboot pad must be placed before the 'spm' partition if that is present.
-    # If 'spm' partition is not present, it must be placed before the 'app'.
+    # MCUboot pad must be placed before the primary application partition.
+    # The primary application partition includes the secure firmware if present.
   size: CONFIG_PM_PARTITION_SIZE_MCUBOOT_PAD
   placement:
     before: [mcuboot_primary_app]