usb: gadget: add multiple definition guards

If f_fs.c and u_serial.c are combined together using #include, which has
been a common practice so far, the pr_vdebug macro is defined multiple
times. Define it only once.

Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 8adc79d..829aba7 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -34,11 +34,15 @@
 /* Debugging ****************************************************************/
 
 #ifdef VERBOSE_DEBUG
+#ifndef pr_vdebug
 #  define pr_vdebug pr_debug
+#endif /* pr_vdebug */
 #  define ffs_dump_mem(prefix, ptr, len) \
 	print_hex_dump_bytes(pr_fmt(prefix ": "), DUMP_PREFIX_NONE, ptr, len)
 #else
+#ifndef pr_vdebug
 #  define pr_vdebug(...)                 do { } while (0)
+#endif /* pr_vdebug */
 #  define ffs_dump_mem(prefix, ptr, len) do { } while (0)
 #endif /* VERBOSE_DEBUG */