fs/ubifs: split long line, use simple asignment

This line has been sitting there unchanged for years now, but it does
not follow current best pratices, that is:
  - do not use imediate assignment,
  - split lines longer than ~80 chars.

Fix that.

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

fs/ubifs/ubifs.mk

@@ -4,7 +4,10 @@
 #
 ################################################################################
 
-UBIFS_OPTS := -e $(BR2_TARGET_ROOTFS_UBIFS_LEBSIZE) -c $(BR2_TARGET_ROOTFS_UBIFS_MAXLEBCNT) -m $(BR2_TARGET_ROOTFS_UBIFS_MINIOSIZE)
+UBIFS_OPTS = \
+	-e $(BR2_TARGET_ROOTFS_UBIFS_LEBSIZE) \
+	-c $(BR2_TARGET_ROOTFS_UBIFS_MAXLEBCNT) \
+	-m $(BR2_TARGET_ROOTFS_UBIFS_MINIOSIZE)
 
 ifeq ($(BR2_TARGET_ROOTFS_UBIFS_RT_ZLIB),y)
 UBIFS_OPTS += -x zlib