drm/amdgpu: Bail earlier when amdgpu.cik_/si_support is not set to 1

drm/amdgpu: Bail earlier when amdgpu.cik_/si_support is not set to 1

Bail from the pci_driver probe function instead of from the drm_driver
load function.

This avoid /dev/dri/card0 temporarily getting registered and then
unregistered again, sending unwanted add / remove udev events to
userspace.

Specifically this avoids triggering the (userspace) bug fixed by this
plymouth merge-request:
https://gitlab.freedesktop.org/plymouth/plymouth/merge_requests/59

Note that despite that being a userspace bug, not sending unnecessary
udev events is a good idea in general.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1490490
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>