xf86drm: Fix error path in drmGetDevice2

xf86drm: Fix error path in drmGetDevice2

In drmGetDevice2 when no local device is found or when
drm_device_has_rdev filters out all devices, *device might be left
uninitialized causing drmGetDevice2 to not return error - since
it's only returned when *device == NULL.

Above leads to crash in the firefox in system with amdgpu.

With this change firefox displays:

libGL error: MESA-LOADER: failed to retrieve device information
libGL error: unable to load driver: amdgpu_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: amdgpu
libGL error: MESA-LOADER: failed to retrieve device information
libGL error: unable to load driver: amdgpu_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: amdgpu

and doesn't crash.

Bugzilla: https://bugs.freedesktop.org/107384
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Mariusz Ceier <mceier+mesa-dev@gmail.com>