[POWERPC] wrapper: Rename offset in offset_devp()

fdt_wrapper_create_node passes a variable called offset to offset_devp(),
which uses said parameter to initialize a local variable called offset.

Due to one of the odder aspects of the C language, the result is an
undefined variable, with no error or warning.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/libfdt-wrapper.c

@@ -44,8 +44,8 @@
 
 #define offset_devp(off)	\
 	({ \
-		int offset = (off); \
-		check_err(offset) ? NULL : (void *)(offset+1); \
+		int _offset = (off); \
+		check_err(_offset) ? NULL : (void *)(_offset+1); \
 	})
 
 #define devp_offset(devp)	(((int)(devp))-1)