mxc_hdmi: Force HDMI hotplug detect and have static EDID

This is based on:
https://github.com/UDOOboard/Kernel_Unico/commit/acca8e0f260f3de326f535b92d6881a9d360cdb3
https://github.com/UDOOboard/Kernel_Unico/commit/a485030198306baa43c6f6131250cc97b31c7f8f

Kernel configuration has to be adapted to enable this functionality - new variables:
CONFIG_FORCE_HDMI_HP_DETECT - Force the presence of an attached HDMI Panel Regardless of the signal present in hpdetect pin.
CONFIG_FORCE_HDMI_FIXED_EDID - Force on-chip MXC HDMI controller to adopt EDID read from external file (/etc/edid.txt) or static internal kernel table.
ARM: dts: wandboard: enable USB OTG

automatic host/peripheral mode selection, plus correct gpio assignment for VBUS enable