drm/amdgpu: fix build_coefficients() argument

gcc -Wextra warns about a function taking an enum argument
being called with a bool:

drivers/gpu/drm/amd/amdgpu/../display/modules/color/color_gamma.c: In function 'apply_degamma_for_user_regamma':
drivers/gpu/drm/amd/amdgpu/../display/modules/color/color_gamma.c:1617:29: warning: implicit conversion from 'enum <anonymous>' to 'enum dc_transfer_func_predefined' [-Wenum-conversion]
 1617 |  build_coefficients(&coeff, true);

It appears that a patch was added using the old calling conventions
after the type was changed, and the value should actually be 0
(TRANSFER_FUNCTION_SRGB) here instead of 1 (true).

Fixes: 55a01d40 ("drm/amd/display: Add user_regamma to color module")
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>