mpc83xx: Add support for -msingle-pic-base

-msingle-pic-base is a new gcc(from 4.6) option for ppc and
it reduces the size of my u-boot with about 4 KB.
While at it, add -fno-jump-tables too to save a
few more bytes.

Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Reviewed-by: Mario Six <mario.six@gdsys.cc>
Tested-by: Mario Six <mario.six@gdsys.cc> (on MPC8308)
diff --git a/arch/powerpc/cpu/mpc83xx/config.mk b/arch/powerpc/cpu/mpc83xx/config.mk
index 14870ee..a07df4d 100644
--- a/arch/powerpc/cpu/mpc83xx/config.mk
+++ b/arch/powerpc/cpu/mpc83xx/config.mk
@@ -3,3 +3,4 @@
 # Copyright 2004 Freescale Semiconductor, Inc.
 
 PLATFORM_CPPFLAGS += -DCONFIG_E300 -msoft-float
+PLATFORM_RELFLAGS += -msingle-pic-base -fno-jump-tables
diff --git a/arch/powerpc/cpu/mpc83xx/start.S b/arch/powerpc/cpu/mpc83xx/start.S
index a3bacf1..c00bb31 100644
--- a/arch/powerpc/cpu/mpc83xx/start.S
+++ b/arch/powerpc/cpu/mpc83xx/start.S
@@ -288,6 +288,9 @@
 	/*------------------------------------------------------*/
 
 	GET_GOT			/* initialize GOT access	*/
+	/* Needed for -msingle-pic-base */
+	bl	_GLOBAL_OFFSET_TABLE_@local-4
+	mflr	r30
 
 	/* r3: IMMR */
 	lis	r3, CONFIG_SYS_IMMR@h