powerpc/85xx: add CONFIG_SYS_TEXT_BASE_SPL for 85xx nand spl build

Introduce a SPL specific CONFIG_SYS_TEXT_BASE_SPL define to be used by
the linker.  This has similiar semantics to CONFIG_SYS_TEXT_BASE however
since SPL is a unqiue image we introduce a new variable to control its
text base address.

Signed-off-by: Haiying Wang <Haiying.Wang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/nand_spl/board/freescale/mpc8569mds/Makefile b/nand_spl/board/freescale/mpc8569mds/Makefile
index d1c0ef8..9c9d63e 100644
--- a/nand_spl/board/freescale/mpc8569mds/Makefile
+++ b/nand_spl/board/freescale/mpc8569mds/Makefile
@@ -24,13 +24,13 @@
 #
 
 NAND_SPL := y
-CONFIG_SYS_TEXT_BASE := 0xfff00000
+CONFIG_SYS_TEXT_BASE_SPL := 0xfff00000
 PAD_TO := 0xfff01000
 
 include $(TOPDIR)/config.mk
 
 LDSCRIPT= $(TOPDIR)/$(CPUDIR)/u-boot-nand_spl.lds
-LDFLAGS	= -Bstatic -T $(LDSCRIPT) -Ttext $(CONFIG_SYS_TEXT_BASE) $(PLATFORM_LDFLAGS)
+LDFLAGS	= -Bstatic -T $(LDSCRIPT) -Ttext $(CONFIG_SYS_TEXT_BASE_SPL) $(PLATFORM_LDFLAGS)
 AFLAGS	+= -DCONFIG_NAND_SPL
 CFLAGS	+= -DCONFIG_NAND_SPL