drm/amd/display: Increase num voltage states to 40

[Description]
If during driver init stage there are greater than 20
intermediary voltage states while constructing the SOC
BB we could hit issues because we will index outside of the
clock_limits array and start overwriting data. Increase the
total number of states to 40 to avoid this issue.

Cc: stable@vger.kernel.org # 6.1+
Reviewed-by: Samson Tam <samson.tam@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>