ARM: shmobile: r8a7790: Configure R-Car GPIO for IRQ_TYPE_EDGE_BOTH

"gpio-rcar: Support IRQ_TYPE_EDGE_BOTH" adds support to the R-Car GPIO
driver for IRQ_TYPE_EDGE_BOTH. As hardware support for this feature is
not universal for all SoCs a flag, has_both_edge_trigger, has been
added to the platform data of the driver to allow this feature to be
enabled.

As the r8a7790 SoC hardware supports this feature enable it.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>