drivers: fpga controller: add fpga api

This adds new FPGA controller which allow to control FPGA chips.

FPGA controller has been created to enable bitstream loading
into the reprogrammable logic. It adds completely new API,
which enables to check status of the FPGA chip, power it on
or off and reset it.

Signed-off-by: Mateusz Sierszulski <msierszulski@internships.antmicro.com>
Signed-off-by: Tomasz Gorochowik <tgorochowik@antmicro.com>