drm: nv04: Fix out of bounds access

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.

Fixes: 2e5702aff395 ("drm/nouveau: fabricate DCB encoder table for iMac G4")
Fixes: 670820c0e6a9 ("drm/nouveau: Workaround incorrect DCB entry on a GeForce3 Ti 200.")
Signed-off-by: Mikhail Kobuk <[email protected]>
Signed-off-by: Danilo Krummrich <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]