usb: gadget: hid: consistently use 2^n - 1 for max values

A maximum value which fits in 16 bits, unsigned, is 65535.
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/gadget/function/f_hid.c

@@ -758,7 +758,7 @@ static struct f_hid_opts_attribute f_hid_opts_##name =			\
 
 F_HID_OPT(subclass, 8, 255);
 F_HID_OPT(protocol, 8, 255);
-F_HID_OPT(report_length, 16, 65536);
+F_HID_OPT(report_length, 16, 65535);
 
 static ssize_t f_hid_opts_report_desc_show(struct f_hid_opts *opts, char *page)
 {