ARM: dts: imx6q-dhcom: Fix ethernet plugin detection problems

ARM: dts: imx6q-dhcom: Fix ethernet plugin detection problems

To make the ethernet cable plugin detection reliable the
power detection of the smsc phy has been disabled.

Fixes: 52c7a088badd ("ARM: dts: imx6q: Add support for the DHCOM iMX6 SoM and PDK2")
Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Fabio Estevam <festevam@gmail.com>
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>