regmap: irq: add support for configuration of trigger type

Some of devices supports the trigger level for interrupt
like rising/falling edge specially for GPIOs. The interrupt
support of such devices may have uses the generic regmap irq
framework for implementation.

Add support to configure the trigger type device interrupt
register via regmap-irq framework. The regmap-irq framework
configures the trigger register only if the details of trigger
type registers are provided.

[Fixed use of terery operator for legibility -- broonie]

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>