The patch adds the following interfaces according the SMARC Spec 1.1
[1] and provided schematics:
 - SMARC SPI0/1
   Note: Since Kontron still uses silicon revisions below 1.3 they have
         add a spi-nor to implement Workaround #1 of erratum ERR006282.
 - SMARC SDIO
 - SMARC LCD
 - SMARC HDMI
 - SMARC Management pins
   Note: Kontron don't route all of these pins to the i.MX6, some are
         routed to the SoM CPLD.
 - SMARC GPIO
 - SMARC CSI Camera
   Note: As specified in [1] the data lanes are shared to cover the
         csi and the parallel case. The case depends on the baseboard so
         muxing the data lanes is not part of this patch.
 - SMARC I2S
 - SMARC Watchdog
   Note: The watchdog output pin is routed to the CPLD and the SMARC
         header. The CPLD performs a reset after a 30s timeout so we
         need to enable the watchdog per default.
 - SMARC module eeprom

Due to the lack of hardware not all of these interfaces are tesetd.

[1] https://sget.org/standards/smarcSigned-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>