drm/amd/display: Fill in dmub_srv fw_version from firmware metadata

[Why]
DMCUB firmware version is now available from firmware metadata block.

We should be passing this into dmub_srv so we can know when to apply
firmware version specific functionality like using CW4 only instead
of the REGION4.

[How]
We don't have the helpers for DM to actually extract out firmware
metadata block themselves.

We could add that and add helpers in DM to grab this, but not every
creation sequence has firmware instruction before dmub_srv_create.

Easiest way to handle this is to fill this in automatically per DM in
the place we do have it - when calculating the region parameters. But
only fill it in if DM already hasn't in case we need to override with
a specific version.

We aren't do anything firmware version specific in dmub_srv_create
today that does require fw_version, so while it's a little unituitive
to do it when calculating region parameters it works for now.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>