ARM: dts: imx6q-dhcom: Add the parallel system bus

Add the parallel system bus provided by the i.MX6 WEIM interface via an
address latch. The OE pin of the latch is controlled by a fixed regulator.
The pin is low active. This is ensured by omitting the regulators property
enable-active-high. The flags value of the gpio property (3rd value), which
is also use to define active high/low, is set to 0 because it is ignored
by gpiolib-of.c.

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: kernel@dh-electronics.com
To: linux-arm-kernel@lists.infradead.org
Signed-off-by: Shawn Guo <shawnguo@kernel.org>