MIPS: Fix CFG_NO_FLASH support

- Fix flash_init call when CFG_NO_FLASH is used
- Remove no more needed flash.c for qemu-mips

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/board/qemu-mips/Makefile b/board/qemu-mips/Makefile
index 23be447..837b6b9 100644
--- a/board/qemu-mips/Makefile
+++ b/board/qemu-mips/Makefile
@@ -25,7 +25,7 @@
 
 LIB	= $(obj)lib$(BOARD).a
 
-COBJS	= $(BOARD).o flash.o
+COBJS	= $(BOARD).o
 SOBJS	= lowlevel_init.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)