x11/nvidia-kmod{-deve]}: Fix loading GSP firmwares for non-legacy variants

[junchoon_dec.sakura.ne.jp]

Summary

Add missing 2 firmware files to x11/nvidia-kmod/pkg-plist
and fixup x11/nvidia-kmod/Makefile not to pick them for
legacy variants that don't have them.

Bumped non-legacy variants only, as pkg for legacy variants
shouldn't be affected with this.

Co-authored by: O. Hartmann

[junchoon_dec.sakura.ne.jp]

Forgot to mention.
PR: 300575