Revert "build: remove harmful -nopad option from mksquashfs"

This reverts commit 1c0290c5cc.

Dropping the nopad can make the padding overflow into the next erase
block on devices using a non-aligned rootfs start. This breaks the jffs2
overlay partition with the following messages:

[   30.343877] jffs2_scan_eraseblock(): End of filesystem marker found at 0x10000
[   30.376512] jffs2: Cowardly refusing to erase blocks on filesystem with no valid JFFS2 nodes
[   30.385253] jffs2: empty_blocks 196, bad_blocks 0, c->nr_blocks 197

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
(cherry picked from commit f11d90a76b)

include/image.mk

@@ -227,7 +227,7 @@ $(eval $(foreach S,$(NAND_BLOCKSIZE),$(call Image/mkfs/jffs2-nand/template,$(S))
 
 define Image/mkfs/squashfs
 	$(STAGING_DIR_HOST)/bin/mksquashfs4 $(call mkfs_target_dir,$(1)) $@ \
-		-noappend -root-owned \
+		-nopad -noappend -root-owned \
 		-comp $(SQUASHFSCOMP) $(SQUASHFSOPT) \
 		-processors 1
 endef