drm/radeon: check that we have a clock before PLL setup
drm/radeon: check that we have a clock before PLL setup

Partially fixes: https://bugzilla.kernel.org/show_bug.cgi?id=75211

Signed-off-by: Christian König <c7ea837d7a46effe4232b086213468b8b31643bf@amd.com>

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