intel_audio_dump: support using base address plus an offset to dump registers

intel_audio_dump: support using base address plus an offset to dump registers

Layout of display and audio registers can be same for different Intel GPUs.
For code sharing, this patches defines functions to
- set the base address of display and audio registers
- dump registers using the base address and an offset

Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Reviewed-by: Haihao Xiang <haihao.xiang@intel.com>