powerpc/kexec: Restore ppc_md.machine_kexec

[Anton Blanchard]

Kyle Moffett points out that mpc85xx has started using the
ppc_md.machine_kexec hook. As such, revert patch c94868788cf2
(powerpc/kexec: Remove ppc_md.machine_kexec).

Signed-off-by: Anton Blanchard <anton at samba.org>
---

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 991d599..fe56a23 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -240,6 +240,12 @@ struct machdep_calls {
 	 * claims to support kexec.
 	 */
 	int (*machine_kexec_prepare)(struct kimage *image);
+
+	/* Called to perform the _real_ kexec.
+	 * Do NOT allocate memory or fail here. We are past the point of
+	 * no return.
+	 */
+	void (*machine_kexec)(struct kimage *image);
 #endif /* CONFIG_KEXEC */
 
 #ifdef CONFIG_SUSPEND
diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index 49a170a..a5f8672 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -87,7 +87,10 @@ void machine_kexec(struct kimage *image)
 
 	save_ftrace_enabled = __ftrace_enabled_save();
 
-	default_machine_kexec(image);
+	if (ppc_md.machine_kexec)
+		ppc_md.machine_kexec(image);
+	else
+		default_machine_kexec(image);
 
 	__ftrace_enabled_restore(save_ftrace_enabled);