KVM: PPC: bookehv: Use lwz/stw instead of PPC_LL/PPC_STL for 32-bit fields

Interrupt code used PPC_LL/PPC_STL macros to load/store some of u32 fields
which led to memory overflow on 64-bit. Use lwz/stw instead.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>