ext4: uninline ext4_inode_journal_mode()

Determining an inode's journaling mode has gotten more complicated over
time.  Move ext4_inode_journal_mode() from an inline function into
ext4_jbd2.c to reduce the compiled code size.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20191209233602.117778-1-ebiggers@kernel.org


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>