target/ppc: Add HASHKEYR and HASHPKEYR SPRs

target/ppc: Add HASHKEYR and HASHPKEYR SPRs

Add the Special Purpose Registers HASHKEYR and HASHPKEYR, which were
introduced by the Power ISA 3.1B. They are used by the new instructions
hashchk(p) and hashst(p).

The ISA states that the Operating System should generate the value for
these registers when creating a process, so it's its responsability to
do so. We initialize it with 0 for qemu-softmmu, and set a random 64
bits value for linux-user.

Signed-off-by: Víctor Colombo <victor.colombo@eldorado.org.br>
Reviewed-by: Lucas Mateus Castro <lucas.araujo@eldorado.org.br>
Message-Id: <20220715205439.161110-2-victor.colombo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>