drm/amd/display: Remove extra pairs of parentheses in dce_calcs.c

The double parentheses are not needed. Removing them fixes multiple
warnings like this when building with clang:

drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:617:42:
  error: equality comparison with extraneous parentheses
    [-Werror,-Wparentheses-equality]
  if ((data->graphics_micro_tile_mode == bw_def_rotated_micro_tiling)) {

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>