Check dimensions passed to drmmode_xf86crtc_resize

When enabling a secondary GPU output, Xorg can try resizing the screen
beyond the limit advertised by the driver, leading to drmModeAddFB
failing and primary GPU outputs turning off. Check for this and bail
instead.

(Ported from amdgpu commit 940c8b39f79789d4d5ddb8ab8d25a8ae05932756)
Acked-by: Alex Deucher <alexander.deucher@amd.com>