ARM: shmobile: r8a7740: Migrate from INTC to GIC

With the added capabilty of the intc_irqpin driver to handle shared
external IRQs, all prerequisites are fulfilled and we are ready to
migrate completely to GIC. This includes the following steps:

- Kconfig:	select ARM_GIC and RENESAS_INTC_IRQPIN
- intc-r8a7740: Throw out all legacy INTC code and init the GIC. We need
  		to mask out all shared IRQs as it is needed by the
		shared intc_irqpin driver.
- setup-r8a7740: Add 4 irqpin devices to handle external IRQs and update
		all IRQ numbers to point to the GIC SPI.
- board-armadillo: Update all IRQ numbers to point to the GIC SPI.
- pfc-r8a7740:	Update all IRQ numbers of the GPIOs to point to the GIC
		SPI.

Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>