samsung-xcover3lte: new device

This MR adds device Samsung Galaxy Xcover 3 aka SM-G388F.

Highlights:

• Creation of flashable PXA bootimg
• Wifi
• Framebuffer console
• uinput api patches for pre 4.4-kernel required by buffyboard and fbp
• Audio (partial)

Notes:

• fbcon is compiled as module to delay loading.
• Some parts/info might be useful for other PXA1908 devices as well.

Cc: @ungeskriptet @LegoLivesMatter @StandaSK @CoderCharmander