[why]
nv14 previously inherited soc bb from generic dcn 2, did not match
watermark values according to memory team

[how]
add nv14 specific soc bb: copy nv2 generic that it was
using from before, but changed num channels to 8
Signed-off-by: NMartin Leung <martin.leung@amd.com>
Reviewed-by: NJun Lei <Jun.Lei@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>