fs: ext4: fix memory leak in ext4_free_branches
Previous commit moved a call to ext4_forget() out of
ext4_free_branches and let ext4_free_blocks() handle calling
bforget().  But that change unfortunately did not replace the call to
ext4_forget() with brelse(), which was needed to drop the in-use count
of the indirect block's buffer head, which lead to a memory leak when
deleting files that used indirect blocks. Fix this.

Thanks to Hugh Dickins for pointing this out.

Commit: https://github.com/androidarmv6/android_kernel_samsung_bcm21553-common/commit/527c8b73eeeea5c5b9e1e084a45d837b70c37099