arm: add 8-byte alignment for ABI compliance before board_init_f

suggested from Daniel Hobi<daniel.hobi@schmid-telecom.ch>

Tested on following boards:
arm1136: qong
armv7: omap3_beagle
arm926ejs: magnesium, tx25

Signed-off-by: Heiko Schocher <hs@denx.de>
cc: Daniel Hobi <daniel.hobi@schmid-telecom.ch>
cc: Albert ARIBAUD <albert.aribaud@free.fr>
diff --git a/arch/arm/cpu/arm720t/start.S b/arch/arm/cpu/arm720t/start.S
index 46050da..da0e61e 100644
--- a/arch/arm/cpu/arm720t/start.S
+++ b/arch/arm/cpu/arm720t/start.S
@@ -138,6 +138,7 @@
 /* Set stackpointer in internal RAM to call board_init_f */
 call_board_init_f:
 	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
+	bic	sp, sp, #7 /* 8-byte alignment for ABI compliance */
 	ldr	r0,=0x00000000
 	bl	board_init_f