drivers: usb: gadget: ether: Fix compiler warning

Latest gcc 6.2 compiler is throwing the below warning for am335x_baltos_defconfig
drivers/usb/gadget/ether.c:501:17: warning: 'mdlm_detail_desc' defined but not used [-Wunused-const-variable=]
 static const u8 mdlm_detail_desc[] = {

Guard mdlm_detail_desc with CONFIG_USB_ETH_SUBSET to avoid the warning

Reported-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
1 file changed