[ATM]: Add CPPFLAGS to byteorder.h check

O= builds produced errors in the shell command because of unfound headers.

Signed-off-by: Ben Collins <bcollins@ubuntu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/atm/Makefile b/drivers/atm/Makefile
index b5077ce..1b16f81 100644
--- a/drivers/atm/Makefile
+++ b/drivers/atm/Makefile
@@ -41,7 +41,7 @@
   # guess the target endianess to choose the right PCA-200E firmware image
   ifeq ($(CONFIG_ATM_FORE200E_PCA_DEFAULT_FW),y)
     byteorder.h			:= include$(if $(patsubst $(srctree),,$(objtree)),2)/asm/byteorder.h
-    CONFIG_ATM_FORE200E_PCA_FW	:= $(obj)/pca200e$(if $(shell $(CC) -E -dM $(byteorder.h) | grep ' __LITTLE_ENDIAN '),.bin,_ecd.bin2)
+    CONFIG_ATM_FORE200E_PCA_FW	:= $(obj)/pca200e$(if $(shell $(CC) $(CPPFLAGS) -E -dM $(byteorder.h) | grep ' __LITTLE_ENDIAN '),.bin,_ecd.bin2)
   endif
 endif