amdsmu: Cezanne support

Add support for Cezanne chips. The only real difference vs
Rembrandt/Phoenix is the idlemask register.

Also simplify getting IP block count by having this straight in struct
amdsmu_product and remove Strix Point from the list for now, as that
doesn't support S0ix and our driver can't handle that.

Reviewed by: mckusick
Approved by: mckusick
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D55594