KVM: PPC: Book3S: Assign boolean values to a bool variable

Fix the following coccinelle warnings:

./arch/powerpc/kvm/book3s_xics.c:476:3-15: WARNING: Assignment of 0/1 to bool variable
./arch/powerpc/kvm/book3s_xics.c:504:3-15: WARNING: Assignment of 0/1 to bool variable

Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1604730382-5810-1-git-send-email-kaixuxia@tencent.com