powerpc/book3s: Fix the MCE code to use CONFIG_KVM_BOOK3S_64_HANDLER

commit id 2ba9f0d has changed CONFIG_KVM_BOOK3S_64_HV to tristate to allow
HV/PR bits to be built as modules. But the MCE code still depends on
CONFIG_KVM_BOOK3S_64_HV which is wrong. When user selects
CONFIG_KVM_BOOK3S_64_HV=m to build HV/PR bits as a separate module the
relevant MCE code gets excluded.

This patch fixes the MCE code to use CONFIG_KVM_BOOK3S_64_HANDLER. This
makes sure that the relevant MCE code is included when HV/PR bits
are built as a separate modules.

Fixes: 2ba9f0d ("kvm: powerpc: book3s: Support building HV and PR KVM as module")
Cc: stable@vger.kernel.org  # v3.14+
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/exceptions-64s.S

@@ -1408,7 +1408,7 @@ machine_check_handle_early:
  bne 9f /* continue in V mode if we are. */
 
 5:
-#ifdef CONFIG_KVM_BOOK3S_64_HV
+#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
  /*
  * We are coming from kernel context. Check if we are coming from
  * guest. if yes, then we can continue. We will fall through