drm/amd/display: remove static from optc31_set_drr

remove static from optc31_set_drr

Reviewed-by: Nevenko Stupar <Nevenko.Stupar@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Eric Bernstein <eric.bernstein@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>