ext4: check ext2/3 compatibility outside handle_mount_opt()

At the parsing phase of mount in the new mount api sb will not be
available so move ext2/3 compatibility check outside handle_mount_opt().
Unfortunately we will lose the ability to show exactly which option is
not compatible.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Link: https://lore.kernel.org/r/20211027141857.33657-8-lczerner@redhat.com


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