drm/amd/display: Use swap() where appropriate

Mostly a cocci-job, but it flat out refused to remove the
declaration in drivers/gpu/drm/amd/display/dc/core/dc.c so
had to do that part manually.

@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: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@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: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>