Include a register that contains SPI controller information.
Currently, it only provides the number of slaves addressable
by the SPI engine.
Original-commit: 1d7d1226e7576bfad484109afd3aad4e78af111b
Modify behavior of clock crossing between radio_clk and radio_clk_2x.
This ensures strobe signals are always asserted for a single
radio_clk_2x cycle and when radio_clk is low.
Original-commit: adb352a2ad81d7c6d70ec5880a787b6bab7d19ba