Updated atusd driver for new hardware. Make use of the interrupt line.

- tools/lib/atusd.c (spi_send_partial, spi_send): removed the old spi_send
  and renamed spi_send_partial to spi_send
- tools/lib/atusd.c (atusd_cycle, spi_send, spi_recv, atusd_open): updated
  for removal of SLP_TR and split of MxSx into MOSI and MISO
- tools/lib/atusd.c (atusd_reset_rf, atusd_open): added delays to precharge
  the capacitors
- tools/lib/atusd.c (atusd_reset, spi_data_in, spi_data_out, spi_finish):
  removed functions for obsolete hardware features
- tools/lib/atusd.c (atusd_reg_read): removed calls to removed functions
- tools/lib/atusd.c (atusd_buf_write, atusd_buf_read, atusd_driver): new
  buffer read/write functions
- tools/atspi-txrx/atspi-txrx.c (init_txrx): set the internal osciallator
  trim only in the USB version. Switch to the external oscillator in the
  uSD version.
- tools/atspi-rssi/atspi-rssi.c (sweep), tools/atspi-txrx/atspi-txrx.c
  (set_channel): wait for the PLL to settle after setting the channel
- tools/include/atspi.h, tools/lib/atspi.c (atspi_interrupt),
  tools/lib/driver.h (struct atspi_driver), tools/lib/atusd.c
  (atusd_interrupt): new function to poll the interrupt line
- tools/atspi-txrx/atspi-txrx.c (receive): only read REG_IRQ_STATUS if
  there is a pending interrupt
- tools/atspi-id/atspi-id.c (usage): print "usage:" as well
- tools/Makefile (upload): upload the atspi tools to the Ben

tools/atspi-rssi/atspi-rssi.c

@@ -30,6 +30,8 @@ static void sweep(struct atspi_dsc *dsc)
 
 	for (chan = 11; chan <= 26; chan++) {
 		atspi_reg_write(dsc, REG_PHY_CC_CCA, chan);
+		/* 150 us, according to AVR2001 section 3.5 */
+		usleep(1000);
 		/*
 		 * No need to explicitly wait for the PPL lock - going USB-SPI
 		 * is pretty slow, leaving the transceiver plenty of time.