sh: intc - remove redundant irq code for sh03, snapgear and titan

This patch removes redundant board specific interrupt code for boards
using sh775x processors and 4 IRQ lines in "Individual Interrupt Mode"
aka IRLM.

Three boards are affected: sh03, snapgear and titan.

The right way to do this is to use cpu specific code provided by intc.
A nice side effect is that sh03 now compiles, board not BROKEN any more.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>