sh: Provide a 29/32-bit physical hint for bootloaders.

Shoves a magic word in to the empty_zero_page section for the
bootloader to work out whether to start the kernel in 29-bit
or 32-bit mode.

[ Renesas CPUs already take care of the initial PMB mappings entirely
  in hardware and decide on 29-bit/32-bit physical depending on which
  pin powered up the CPU, so this is mostly for ST parts. -- PFM ].
Signed-off-by: NStuart Menefy <stuart.menefy@st.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/kernel/head_32.S

@@ -32,7 +32,11 @@ ENTRY(empty_zero_page)
 	.long	1		/* LOADER_TYPE */
 	.long	0x00360000	/* INITRD_START */
 	.long	0x000a0000	/* INITRD_SIZE */
-	.long	0
+#ifdef CONFIG_32BIT
+	.long	0x53453f00 + 32	/* "SE?" = 32 bit */
+#else
+	.long	0x53453f00 + 29	/* "SE?" = 29 bit */
+#endif
 1:
 	.skip	PAGE_SIZE - empty_zero_page - 1b