powerpc: Fix section mismatch warning

Add __init to MMU_setup() which uses __initdata boot_command_line.
Also MMU_setup() is only called from MMU_init(), which is also __init.

Warning appeared since commit 3e47d147.

Fixes: 3e47d147 ("powerpc: Remove powerpc specific cmd_line")
Signed-off-by: Fabian Frederick <fabf@skynet.be>
[mpe: Update changelog]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/init_32.c

@@ -103,7 +103,7 @@ unsigned long __max_low_memory = MAX_LOW_MEM;
 /*
  * Check for command-line options that affect what MMU_init will do.
  */
-void MMU_setup(void)
+void __init MMU_setup(void)
 {
 	/* Check for nobats option (used in mapin_ram). */
 	if (strstr(boot_command_line, "nobats")) {