[PATCH] usb: Restore the usb_header label

[Fabio Estevam]

Commit caa93d9bd2d7 ("usb: Fix up movement of USB core kerneldoc location")
removed the reference to the _usb_header label by mistake, which causes the
following htmldocs build warning:

Documentation/driver-api/usb/writing_usb_driver.rst:129: WARNING: undefined label: usb_header

Restore the label.

Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Fixes: caa93d9bd2d7 ("usb: Fix up movement of USB core kerneldoc location") 
Signed-off-by: Fabio Estevam <festevam@xxxxxxxxx>
---
 Documentation/driver-api/usb/usb.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/driver-api/usb/usb.rst b/Documentation/driver-api/usb/usb.rst
index 820e867af45a..2c94ff2f4385 100644
--- a/Documentation/driver-api/usb/usb.rst
+++ b/Documentation/driver-api/usb/usb.rst
@@ -123,6 +123,8 @@ are in ``drivers/usb/common/common.c``.
 In addition, some functions useful for creating debugging output are
 defined in ``drivers/usb/common/debug.c``.
 
+.. _usb_header:
+
 Host-Side Data Types and Macros
 ===============================
 
-- 
2.25.1