drm/amd/display: Remove duplicated function signature from dcn3.01 DCCG

In the header file dc/dcn301/dcn301_dccg.h, the function dccg301_create
is declared twice, so remove duplication.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: David Tadokoro <davidbtadokoro@usp.br>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>