drm/amd/display: change name from dc_link_get_verified_link_cap to dc_link_get_link_cap

[Why]
DM doesn't need to know which link cap is being retrieved ( verified
 or preferred ).  Let DC figure it out.

[How]
Change name.

Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha &lt;Bhawanpreet <Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>