usb: gadget: legacy: printer: Remove unused variable 'driver_desc'

Fixes the following W=1 kernel build warning(s):

 drivers/usb/gadget/legacy/printer.c:24:19: warning: ‘driver_desc’ defined but not used [-Wunused-const-variable=]

Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200706133341.476881-4-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/legacy/printer.c

@@ -21,7 +21,6 @@ USB_GADGET_COMPOSITE_OPTIONS();
 #define DRIVER_VERSION		"2015 FEB 17"
 
 static const char shortname [] = "printer";
-static const char driver_desc [] = DRIVER_DESC;
 
 #include "u_printer.h"