fs/ext2: fix double quoted label

Since the commit 6dd7bbb591, the label does
not need anymore to be quoted. Even worse it *must* not be simple-quoted,
unless the label will contain the double-quotes from the config variable
BR2_TARGET_ROOTFS_EXT2_LABEL.

The commit mentionned above has replaced echo by printf:
-	echo "$$(ROOTFS_$(2)_CMD)" >> $$(FAKEROOT_SCRIPT)
+	$$(call PRINTF,$$(ROOTFS_$(2)_CMD)) >> $$(FAKEROOT_SCRIPT)

Since this commit the rootfs label contains extra double-quotes.
$ blkid
/dev/mmcblk0: LABEL=""BR 2016.08"" UUID="xxx"
                     ^          ^

With this fix, the extra double-quotes have disappeared:
/dev/mmcblk0: LABEL="BR 2016.11-rc2" UUID="yyy"

Signed-off-by: Gaël PORTAY <gael.portay@savoirfairelinux.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

fs/ext2/ext2.mk

@@ -20,12 +20,11 @@ ifneq ($(strip $(BR2_TARGET_ROOTFS_EXT2_RESBLKS)),0)
 EXT2_OPTS += -r $(BR2_TARGET_ROOTFS_EXT2_RESBLKS)
 endif
 
-# Not qstrip-ing the variable, because it may contain spaces, but we must
-# qstrip it when checking. Furthermore, we need to further quote it, so
-# that the quotes do not get eaten by the echo statement when creating the
-# fakeroot script
-ifneq ($(call qstrip,$(BR2_TARGET_ROOTFS_EXT2_LABEL)),)
-EXT2_OPTS += -l '$(BR2_TARGET_ROOTFS_EXT2_LABEL)'
+# qstrip results in stripping consecutive spaces into a single one. So the
+# variable is not qstrip-ed to preserve the integrity of the string value.
+EXT2_LABEL := $(subst ",,$(BR2_TARGET_ROOTFS_EXT2_LABEL))
+ifneq ($(EXT2_LABEL),)
+EXT2_OPTS += -l "$(EXT2_LABEL)"
 endif
 
 ROOTFS_EXT2_DEPENDENCIES = host-mke2img