modesetting: Record non-desktop kernel property at PreInit time

Save any value of the kernel non-desktop property in the xf86Output
structure to avoid non-desktop outputs in the default configuration.

[Also bump randrproto requirement to a version that defines
RR_PROPERTY_NON_DESKTOP - ajax]

Signed-off-by: Keith Packard <keithp@keithp.com>
(Ported from xserver commit b91c787c4cd2d20685db69426c539938c556128a)
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
(Ported from amdgpu commit 14db71a606128c4a207f43298809af279b77e2a8)
Acked-by: Alex Deucher <alexander.deucher@amd.com>