drm/amdkfd: Use dev_* instead of pr_* for messages

To get the device context, replace pr_ with dev_ functions.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>