arm: config: cbi/hb Build MMC_BLOCK directly into kernel

This was set to =m which basically made the CBi/HB unbootable.
Let's fix this as we would really like to make sure our devices
boot all the way to userspace.
add audio and wireless firmware
work around non-working uhs mode
add README.md
add a .config suitable for fc20
replace current config with imx_v7_cbi_hb_defconfig