MFC r315242: Fix late and noauto with geli swap

With the following in /etc/fstab:

/dev/gpt/swap.eli none swap sw,late 0 0

swap will not be enabled, with `swapon -aL' complaining:

swapon: Invalid option: late

This happens because swap_on_geli_args() which parses geli arguments
out of all mount options does not expect late or noauto among them.
Fix this by explicitly allowing these arguments.

Reviewed by: jilles
Approved by: jilles
Differential Revision: D9835