irqchip/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>
Cc: Damien Riegel <damien.riegel@savoirfairelinux.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20160209111920.1ec318bd@endymion


Signed-off-by: Jason Cooper <jason@lakedaemon.net>