ext4: Remove unused match_table_t tokens

ext4: Remove unused match_table_t tokens

Remove unused match_table_t, slim down mount_opts structure by removing
unnecessary definitions, remove redundant MOPT_ flags and clean up
ext4_parse_param() by converting the most of the if/else branching to
switch except for the MOPT_SET/MOPT_CEAR handling.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Link: https://lore.kernel.org/r/20211027141857.33657-14-lczerner@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>