Add generic irq_chip for TX39/TX49 SoCs. This can be replace jmr3927_irq_irc, tx4927_irq_pic_type and tx4938_irq_pic_type. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>