video: vga16fb: Fix logic that checks for the display standard

The vga16fb framebuffer driver supports both Enhanced Graphics Adapter
(EGA) and Video Graphics Array (VGA) 16 color graphic cards.

But the logic to check whether the EGA or VGA standard are used is not
correct. It just checks if screen_info.orig_video_isVGA is set, but it
should check if is set to VIDEO_TYPE_VGAC instead.

This means that it assumes to be VGA even if is set to VIDEO_TYPE_EGAC.

All non-x86 architectures though treat orig_video_isVGA as a boolean so
only do the change for x86 and keep the old logic for the other arches.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Kris Karas <bugs-a21@moonlit-rail.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220110095625.278836-2-javierm@redhat.com