drm/amd/display: reduce stack size in dcn32 dml (v2)

Move additional dummy structures off the stack and into
the dummy vars structure.

Fixes the following:
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c: In function 'DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation':
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1659:1: error: the frame size of 2144 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
 1659 | }
      | ^
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c: In function 'dml32_ModeSupportAndSystemConfigurationFull':
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:3799:1: error: the frame size of 2464 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
 3799 | } // ModeSupportAndSystemConfigurationFull
      | ^

v2: move more stuff to dummy structure, fix init order (Alex)

Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>