Input: ts4800 - add hardware dependency

The Technologic Systems TS-4800 is an i.MX515 board, so its drivers
are useless unless building a SOC_IMX51 kernel, except for build
testing purposes.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>