power: domain: ti: Extend use of PTCMD and PTSTAT registers for high PDs

It is possible for power domain IDs to be great than 31. If this
happens, the PTCMD and PTSTAT registers must overflow into adjacent
corresponding PTCMD_H and PTSTAT_H registers for each. Update the driver
to account for this.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>