ext4: only call sync_filesystm() when remounting read-only
ext4: only call sync_filesystm() when remounting read-only

This is the only time it is required for ext4.

Signed-off-by: "Theodore Ts'o" <4ed386e0495d3e109932df055831d9ec2f824927@mit.edu>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs