arm nomadik: rename board to nhk8815

This is an error in my side in the initial submission: nobody
calls it ""nmdk8815", it's "nomadik hardware kit", nhk8815, instead.

Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>

board/st/nhk8815/Makefile

@@ -29,7 +29,7 @@ include $(TOPDIR)/config.mk
 
 LIB	= $(obj)lib$(BOARD).a
 
-COBJS	:= nmdk8815.o
+COBJS	:= nhk8815.o
 SOBJS	:= platform.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)