[MIPS] Fix CONFIG_BOOT_RAW.

This was broken by 017e3a492683b32d17dcd1b13b279745cc656073 (lmo) /
396a2ae0 (kernel.org).
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/head.S

@@ -136,7 +136,8 @@ EXPORT(_stext)
 	 * kernel load address.  This is needed because this platform does
 	 * not have a ELF loader yet.
 	 */
-	__INIT
+FEXPORT(__kernel_entry)
+	j	kernel_entry
 #endif
 
 	__INIT_REFOK