kernel: Enable kmod-hid-generic driver when selecting usb-hid

kmod-hid-generic needs to be selected when enabling usb-hid in order to get generic devices working.

This fixes keyboards support in linux 3.3+ kernels.
https://dev.openwrt.org/ticket/12631
https://dev.openwrt.org/ticket/12686



Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

SVN-Revision: 40932