drm/vmwgfx: Remove getparam error message

The mesa winsys sometimes uses unimplemented parameter requests to
check for features. Remove the error message to avoid bloating the
kernel log.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>