drm/amd/display: fix typo in function name

s/amdgpu_dm_find_first_crct_matching_connector/
amdgpu_dm_find_first_crtc_matching_connector/

And while here, make it static.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>