drm/amd/amdgpu: Fix warnings in amdgpu _object, _ring.c

Fix below warnings reported by checkpatch:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: static const char * array should probably be static const char * const
WARNING: space prohibited between function name and open parenthesis '('
WARNING: braces {} are not necessary for single statement blocks
WARNING: Symbolic permissions 'S_IRUGO' are not preferred. Consider using octal permissions '0444'.

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