USB: ffs-test: fix header path

When compiling this program the functionfs.h header cannot be found, producing:
ffs-test.c:40: fatal error: linux/usb/functionfs.h: No such file or directory

This patch also fixes the following warning:
ffs-test.c:453: warning: format ‘%4d’ expects type ‘int’, but argument 3 has type ‘size_t’
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

tools/usb/ffs-test.c

@@ -37,7 +37,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include <linux/usb/functionfs.h>
+#include "../../include/linux/usb/functionfs.h"
 
 
 /******************** Little Endian Handling ********************************/
@@ -450,7 +450,7 @@ empty_out_buf(struct thread *ignore, const void *buf, size_t nbytes)
 		    len, expected, *p);
 		for (p = buf, len = 0; len < nbytes; ++p, ++len) {
 			if (0 == (len % 32))
-				fprintf(stderr, "%4d:", len);
+				fprintf(stderr, "%4zd:", len);
 			fprintf(stderr, " %02x", *p);
 			if (31 == (len % 32))
 				fprintf(stderr, "\n");