drm: nv04: Fix out of bounds access

In the Linux kernel, the following vulnerability has been resolved:

drm: nv04: Fix out of bounds access

When Output Resource (dcb->or) value is assigned in

fabricate_dcb_output(), there may be out of bounds access to

dac_users array in case dcb->or is zero because ffs(dcb->or) is

used as index there.

The 'or' argument of fabricate_dcb_output() must be interpreted as a

number of bit to set, not value.

Utilize macros from 'enum nouveau_or' in calls instead of hardcoding.

Found by Linux Verification Center (linuxtesting.org) with SVACE.