[MIPS] Fix modpost warning in raw binary builds.

  MODPOST vmlinux.o
WARNING: vmlinux.o(.text+0x478): Section mismatch: reference to .init.text:start_kernel (between '_stext' and 'run_init_process')
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/head.S

@@ -140,7 +140,7 @@
 
 EXPORT(_stext)
 
-#ifndef CONFIG_BOOT_RAW
+#ifdef CONFIG_BOOT_RAW
 	/*
 	 * Give us a fighting chance of running if execution beings at the
 	 * kernel load address.  This is needed because this platform does
@@ -149,6 +149,8 @@ EXPORT(_stext)
 	__INIT
 #endif
 
+	__INIT_REFOK
+
 NESTED(kernel_entry, 16, sp)			# kernel entry point
 
 	kernel_entry_setup			# cpu specific setup