usb: typec_altmode: add a missing "@" at a kernel-doc parameter

Without that, the parameter is not properly parsed:
	include/linux/usb/typec_altmode.h:132: warning: Function parameter or member 'altmode' not described in 'typec_altmode_get_orientation'
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/70dc4c5d744cf1fe9a0efe6b85deaa0489628282.1656409369.git.mchehab@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/usb/typec_altmode.h

@@ -124,7 +124,7 @@ struct typec_altmode *typec_match_altmode(struct typec_altmode **altmodes,
 
 /**
  * typec_altmode_get_orientation - Get cable plug orientation
- * altmode: Handle to the alternate mode
+ * @altmode: Handle to the alternate mode
  */
 static inline enum typec_orientation
 typec_altmode_get_orientation(struct typec_altmode *altmode)