powerpc/64s: Prevent fallthrough to hash TLB flush when using radix

powerpc/64s: Prevent fallthrough to hash TLB flush when using radix

In the fix reconnecting hash__tlb_flush() to tlb_flush() the
void return on radix__tlb_flush() was not restored and subsequently
falls through to the restored hash__tlb_flush().

Guard hash__tlb_flush() under an else to prevent this.

Fixes: 1665c027afb2 ("powerpc/64s: Reconnect tlb_flush() to hash__tlb_flush()")
Reported-by: "Erhard F." <erhard_f@mailbox.org>
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230217011434.115554-1-bgray@linux.ibm.com