drm/radeon: Prefer dev_* variant over printk

drm/radeon: Prefer dev_* variant over printk

Changed from pr_err/info to dev_* variants so that
we get better debug info when there are multiple GPUs
in the system.

Fixes: 09edeb4c1680 ("drm/radeon: Prefer pr_err/_info over printk")
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>