efs: convert efs to use the new mount api

Convert the efs filesystem to use the new mount API.

Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
Link: https://lore.kernel.org/r/20240220003318.166143-1-bodonnel@redhat.com


Signed-off-by: Christian Brauner <brauner@kernel.org>