libbladeRF: add initial XB-200 transverter support
bladeRF-cli: add initial support for XB-200
hdl: add XB-200 support

This commit introduce XB-200 support in HDL. XB support introduces a new
direction configurable GPIO bank that is used to control peripherals on the XB
port. The xb_mode for the XB-200 board overrides exp_goio so it is used as
a chipselect pin for the ADF4351.
hdl: swap XB SPI pins

To match the design of the XB-200 these pins will now be changed. This change is
backward compatible.
hdl: fixup pin assignment for exp_spi_clock