fpga: region: Add reset support to the fpga region

fpga: region: Add reset support to the fpga region

Many of the fpga regions have a reset that has to be
asserted after the bit file programming. Add support
for the same in case there is no reset phandle passed
no action is taken so it is backward compatible.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>