staging: gpib: Add comment for mutex define

Handle checkpatch CHECK message

Signed-off-by: Dave Penkler <[e-mail]>
Reviewed-by: Dan Carpenter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/gpib/agilent_82357a/agilent_82357a.c

···
 
 #define MAX_NUM_82357A_INTERFACES 128
 static struct usb_interface *agilent_82357a_driver_interfaces[MAX_NUM_82357A_INTERFACES];
-DEFINE_MUTEX(agilent_82357a_hotplug_lock);
+DEFINE_MUTEX(agilent_82357a_hotplug_lock); // protect board insertion and removal
 
 static unsigned int agilent_82357a_update_status(gpib_board_t *board, unsigned int clear_mask);