drm/amdgpu: fix num_crtc on CZ
drm/amdgpu: fix num_crtc on CZ

Hw only has 3 crtcs.  copy paste typo.

Signed-off-by: Alex Deucher <08dc22c6156113f2deff178e35e3ed9b24d6af9e@amd.com>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs