drm/amdkfd: Use hex print format for pasid

Since KFD pasid starts from 0x8000 (32768 in decimal), it is better
perceived as a hex number. Meanwhile, change the pasid type from
unsigned int to uint16_t to be consistent throughout the code.

Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>