drm/radeon: fix typo in fetching mpll params

Copy-paste typo.  Value should be 0-2, not 0-1.

Noticed-by: Sylvain BERTRAND <sylware@legeek.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
1 file changed