ext4: Add fs parameter specifications for mount options

Create an array of fs_parameter_spec called ext4_param_specs to
hold the mount option specifications we're going to be using with the
new mount api.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Link: https://lore.kernel.org/r/20211027141857.33657-3-lczerner@redhat.com


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