drm/amdgpu: Clean up style problems in mmhub_v2_3.c

Fixes the following:

ERROR: code indent should use tabs where possible
WARNING: Missing a blank line after declarations
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: suspect code indent for conditional statements (8, 24)
+       if (!(data & (DAGB0_CNTL_MISC2__DISABLE_WRREQ_CG_MASK |
[...]
+                       *flags |= AMD_CG_SUPPORT_MC_MGCG;

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@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>