sh: place board lowlevel_init code in the beginning of .text

Reference lowlevel_init of all supported SH2A/SH3/SH4/SH4A boards
from a shared linker script, the lowlevel_init function will be called
by a relative address.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/sh/cpu/u-boot.lds

@@ -31,7 +31,7 @@ SECTIONS
 	.text :
 	{
 		KEEP(*/start.o		(.text))
-		KEEP(CONFIG_BOARDDIR/lowlevel_init.o	(.spiboot1.text))
+		KEEP(CONFIG_BOARDDIR/lowlevel_init.o	(.text .spiboot1.text))
 		KEEP(*(.spiboot2.text))
 		. = ALIGN(8192);
 		common/env_embedded.o	(.ppcenv)