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: 1665c027 ("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

arch/powerpc/include/asm/book3s/64/tlbflush.h

@@ -97,8 +97,8 @@ static inline void tlb_flush(struct mmu_gather *tlb)
 {
 	if (radix_enabled())
 		radix__tlb_flush(tlb);
-
-	return hash__tlb_flush(tlb);
+	else
+		hash__tlb_flush(tlb);
 }
 
 #ifdef CONFIG_SMP