drm/amd/display: Fix DPIA number and driver ID field issue

drm/amd/display: Fix DPIA number and driver ID field issue

[Why]
The DPIA number field is 6 bits in the spec.
In dp_type, it only defines 5 bits.
The driver ID is only 4 bits in the spec.

[How]
Set DPIA number field size to 6.
And only update 4 bits for driver id.

Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Signed-off-by: Cruise Hung <Cruise.Hung@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>