fips: ensure fs module for /boot is installed

fips: ensure fs module for /boot is installed

When using dracut with  --hostonly and --no-hostonly-default-device,
/boot will be inaccessible as dracut will most fs modules unless
specified. But FIPS require /boot to be accessible, and it will try
to mount it on boot. It will fail if corresponding fs module is missing.

For most case /boot will be a simple partition, include the fs module
will be enough for FIPS to mount it. For other cases users have to pass
extra parameters by themselves.

Suggested-by: Kenneth Dsouza <kdsouza@redhat.com>
Signed-off-by: Kairui Song <kasong@redhat.com>