powerpc/kvm: Fix ifdef to remove build warning

powerpc/kvm: Fix ifdef to remove build warning

When compiling for pseries or powernv defconfig with "make C=1",
these warning were reported bu sparse tool in powerpc/kernel/kvm.c

arch/powerpc/kernel/kvm.c:635:9: warning: switch with no cases
arch/powerpc/kernel/kvm.c:646:9: warning: switch with no cases

Currently #ifdef were added after the switch case which are specific
for BOOKE and PPC_BOOK3S_32. These are not enabled in pseries/powernv
defconfig. Fix it by moving the #ifdef before switch(){}

Fixes: cbe487fac7fc0 ("KVM: PPC: Add mtsrin PV code")
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250518044107.39928-1-maddy@linux.ibm.com