KVM: RISC-V: Use "new" memslot instead of userspace memory region

KVM: RISC-V: Use "new" memslot instead of userspace memory region

Get the slot ID, hva, etc... from the "new" memslot instead of the
userspace memory region when preparing/committing a memory region.  This
will allow a future commit to drop @mem from the prepare/commit hooks
once all architectures convert to using "new".

Opportunistically wait to get the various "new" values until after
filtering out the DELETE case in anticipation of a future commit passing
NULL for @new when deleting a memslot.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <543608ab88a1190e73a958efffafc98d2652c067.1638817640.git.maciej.szmigiero@oracle.com>