mpc83xx: Removed unused file resetvec.S for mpc83xx cpu

Removed unused file resetvec.S for mpc83xx cpu

Signed-off-by: Tanya Jiang <tanya.jiang@freescale.com>
diff --git a/cpu/mpc83xx/Makefile b/cpu/mpc83xx/Makefile
index b2a6b3e..1aa0005 100644
--- a/cpu/mpc83xx/Makefile
+++ b/cpu/mpc83xx/Makefile
@@ -27,7 +27,7 @@
 
 LIB	= $(obj)lib$(CPU).a
 
-START	= start.o resetvec.o
+START	= start.o
 COBJS	= traps.o cpu.o cpu_init.o speed.o interrupts.o \
 	  i2c.o spd_sdram.o