gpu: amd: Clean up errors in ppatomfwctrl.h

Fix the following errors reported by checkpatch:

ERROR: open brace '{' following struct go on the same line

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

gpu: amd: replace open-coded offsetof() with builtin

The two AMD drivers have their own custom offsetof() implementation
that now triggers a warning with recent versions of clang:

drivers/gpu/drm/radeon/radeon_atombios.c:133:14: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]

Change all the instances to use the normal offsetof() provided
by the kernel that does not have this problem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/pm: optimize the power related source code layout

The target is to provide a clear entry point(for power routines).
Also this can help to maintain a clear view about the frameworks
used on different ASICs. Hopefully all these can make power part
more friendly to play with.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>