drm/radeon: Cleanup radeon/radeon_fence.c

drm/radeon: Cleanup radeon/radeon_fence.c

Fixes the following:

WARNING: Possible repeated word: 'Fences'
WARNING: Missing a blank line after declarations
WARNING: braces {} are not necessary for single statement blocks
WARNING: braces {} are not necessary for any arm of this statement
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: quoted string split across lines
WARNING: Block comments use * on subsequent lines
WARNING: Block comments use a trailing */ on a separate line

Cc: Guchun Chen <guchun.chen@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>