ext4: rename {exit,init}_ext4_*() to ext4_{exit,init}_*()

This is a cleanup to avoid namespace leaks out of fs/ext4

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --cc fs/ext4/block_validity.c
Simple merge

diff --cc fs/ext4/ext4.h
Simple merge

diff --cc fs/ext4/mballoc.c
Simple merge

diff --cc fs/ext4/page-io.c
Simple merge

diff --cc fs/ext4/super.c
Simple merge

diff --cc fs/ext4/xattr.c
Simple merge

diff --cc fs/ext4/xattr.h
Simple merge