KVM: PPC: Read out syscall instruction on trap

We have a few traps where we cache the instruction that cause the trap
for analysis later on. Since we now need to be able to distinguish
between SC 0 and SC 1 system calls and the only way to find out which
is which is by looking at the instruction, we also read out the instruction
causing the system call.

Signed-off-by: Alexander Graf <agraf@suse.de>