irqchip: Add LPC32xx interrupt controller driver

The change adds improved support of NXP LPC32xx MIC, SIC1 and SIC2
interrupt controllers.

This is a list of new features in comparison to the legacy driver:
* irq types are taken from device tree settings, no more need to
  hardcode them,
* old driver is based on irq_domain_add_legacy, which causes problems
  with handling MIC hardware interrupt 0 produced by SIC1,
* there is one driver for MIC, SIC1 and SIC2, no more need to handle
  them separately, e.g. have two separate handlers for SIC1 and SIC2,
* the driver does not have any dependencies on hardcoded register
  offsets,
* the driver is much simpler for maintenance,
* SPARSE_IRQS option is supported.

Legacy LPC32xx interrupt controller driver was broken since commit
76ba59f836 ("genirq: Add irq_domain-aware core IRQ handler"), which
requires a private interrupt handler, otherwise any SIC1 generated
interrupt (mapped to MIC hwirq 0) breaks the kernel with the message
"unexpected IRQ trap at vector 00".

The change disables compilation of a legacy driver found at
arch/arm/mach-lpc32xx/irq.c, the file will be removed in a separate
commit.

Fixes: 76ba59f836 ("genirq: Add irq_domain-aware core IRQ handler")
Tested-by: Sylvain Lemieux <slemieux.tyco@gmail.com>
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/mach-lpc32xx/phy3250.c

@@ -206,7 +206,6 @@ static const char *const lpc32xx_dt_compat[] __initconst = {
 DT_MACHINE_START(LPC32XX_DT, "LPC32XX SoC (Flattened Device Tree)")
 	.atag_offset	= 0x100,
 	.map_io		= lpc32xx_map_io,
-	.init_irq	= lpc32xx_init_irq,
 	.init_machine	= lpc3250_machine_init,
 	.dt_compat	= lpc32xx_dt_compat,
 MACHINE_END