drm/amdgpu/powerplay: Use swap() where appropriate

@swap@
identifier TEMP;
expression A,B;
@@
- TEMP = A;
- A = B;
- B = TEMP;
+ swap(A, B);

@@
type T;
identifier swap.TEMP;
@@
(
- T TEMP;
|
- T TEMP = {...};
)
... when != TEMP

Cc: Rex Zhu <rex.zhu@amd.com>
Cc: Evan Quan <evan.quan@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>