ext2: use ext2_group_first_block_no()

Use ext2_group_first_block_no() and assign the return values to
ext2_fsblk_t variables.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc fs/ext2/inode.c
Simple merge

diff --cc fs/ext2/super.c
Simple merge

diff --cc fs/ext2/xattr.c
Simple merge