ext4: Make sure ext4_dirty_inode() updates the inode in no journal mode

This patch a problem that ext4_dirty_inode() was not calling
ext4_mark_inode_dirty() if the current_handle is not valid, which it
is the case in no journal mode.

It also removes a test for non-matching transaction which can never
happen.

Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>