powerpc/85xx: fix compile error without CONFIG_CRASH_DUMP

Since commit 5c4233c ("powerpc/kdump: Split KEXEC_CORE and
CRASH_DUMP dependency"), crashing_cpu is not available without
CONFIG_CRASH_DUMP. Fix compile error on 64-BIT 85xx owing to this
change.

Fixes: 5c4233c ("powerpc/kdump: Split KEXEC_CORE and CRASH_DUMP dependency")
Cc: stable@vger.kernel.org # v6.9+
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Closes: https://lore.kernel.org/all/fa247ae4-5825-4dbe-a737-d93b7ab4d4b9@xenosoft.de/
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240510080757.560159-1-hbathini@linux.ibm.com

Author: hbathini

arch/powerpc/platforms/85xx/smp.c

@@ -398,6 +398,7 @@ static void mpc85xx_smp_kexec_cpu_down(int crash_shutdown, int secondary)
 	hard_irq_disable();
 	mpic_teardown_this_cpu(secondary);
 
+#ifdef CONFIG_CRASH_DUMP
 	if (cpu == crashing_cpu && cpu_thread_in_core(cpu) != 0) {
 		/*
 		 * We enter the crash kernel on whatever cpu crashed,
@@ -406,9 +407,11 @@ static void mpc85xx_smp_kexec_cpu_down(int crash_shutdown, int secondary)
 		 */
 		disable_threadbit = 1;
 		disable_cpu = cpu_first_thread_sibling(cpu);
-	} else if (sibling != crashing_cpu &&
-		   cpu_thread_in_core(cpu) == 0 &&
-		   cpu_thread_in_core(sibling) != 0) {
+	} else if (sibling == crashing_cpu) {
+		return;
+	}
+#endif
+	if (cpu_thread_in_core(cpu) == 0 && cpu_thread_in_core(sibling) != 0) {
 		disable_threadbit = 2;
 		disable_cpu = sibling;
 	}