ARM: dts: imx7d-pinfunc: fix UART pinmux defines

The UART pinmux defines for the pins which are part of the LPSR
pinmux controller are wrong: Output signals configure the input
sel value and the pinmux defines allow not to distinguish between
DCE/DTE mode. Follow the usual pattern using DTE/DCE as part of
the define to denote the two UART configuration options.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>