drm/amd/display: Fix a potential NULL dereference

The debug printk dereferences "link->link_enc" before we have ensured
that it is non-NULL.  Fix this potential NULL derefence by moving the
printk after the check.

Fixes: 64ff0882 ("drm/amd/display: Log link/connector info provided in BIOS object table")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>