drm/amdgpu: Clean up errors in gfx_v7_0.c

Fix the following errors reported by checkpatch:

ERROR: that open brace { should be on the previous line
ERROR: trailing statements should be on next line
ERROR: open brace '{' following struct go on the same line
ERROR: space prohibited before that '++' (ctx:WxB)

Signed-off-by: Ran Sun <sunran001@208suo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>