drm/amd/amdgpu: Fix errors & warnings in mmhub_v1_8.c

Fix below errors & warnings reported by checkpatch:

ERROR: code indent should use tabs where possible
WARNING: please, no space before tabs
WARNING: please, no spaces at the start of a line
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
ERROR: space prohibited before that '++' (ctx:WxB)
WARNING: Block comments use a trailing */ on a separate line

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>