f_accessory.h: Update USB accessory kernel driver header file

Bug: 5051683

Change-Id: I24fb640f24439f0010735eaa8e1e7b2767c353ea
Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/libc/kernel/common/linux/usb/f_accessory.h b/libc/kernel/common/linux/usb/f_accessory.h
index 7ee9b7f..97346b7 100644
--- a/libc/kernel/common/linux/usb/f_accessory.h
+++ b/libc/kernel/common/linux/usb/f_accessory.h
@@ -40,4 +40,5 @@
 #define ACCESSORY_GET_STRING_VERSION _IOW('M', 4, char[256])
 #define ACCESSORY_GET_STRING_URI _IOW('M', 5, char[256])
 #define ACCESSORY_GET_STRING_SERIAL _IOW('M', 6, char[256])
+#define ACCESSORY_IS_START_REQUESTED _IO('M', 7)
 #endif