drm/amdgpu/jpeg: Move parse_cs to amdgpu_jpeg.c

Rename jpeg_v2_dec_ring_parse_cs to amdgpu_jpeg_dec_parse_cs
and move it to amdgpu_jpeg.c as it is shared among jpeg versions.

Signed-off-by: Sathishkumar S <sathishkumar.sundararaju@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>