hdl: driver: change GPIO register size to 32 bits

GPIO reads and writes can now 8 bits of the 32bit nios_gpio (GPIO register)
register at a time by subscripting into the register with the uart_cmd.addr
variable. addr 0 operates on the least significant byte, addr 1 operates on the
second least significant byte.
hdl: driver: add subscripted VCTCXO read/write support

The VCTCXO DAC operations now have the same functionality as GPIO reads/writes.
The Nios core stores the least significant byte in a temporary variable and only
performs a write to the DAC when the most sigificant byte of the 16bit DAC value
is written to it by the host.

This commit does not address host endianness.
linux: only create a bladeRF device on interface 0

The linux USB stack creates a device for each interface. Since bladeRF has 3
interfaces, 3 different /dev/bladerfX files are created.
linux: stop driver from submitting URBs once device has been disconnected

This fixes and issues where the drive would continue to submit URBs even after
the device was unplugged, and the usb_device was freed from the usb core causing
kernel panics.
hdl: Swapping 32-bit places for I and Q.

The host has an easier time dealing with samples as I being first
followed by Q.
cli: Changed print out of samplerate for RX and TX to be consistent.
cli: Set frequency bounds checking.
lib: Add band selection when setting frequency.
cli: Fixed definition of "open" command names.

What was supposed to be a NULL terminator had quotes around it,
yielding unruly behavior.
Fix missing architecture for qpsk_tx rev
Merge pull request #12 from rtucker/bladerf

Fix missing architecture for qpsk_tx rev
Changing README to be more accurate and descriptive.
fx3: Created README for building instructions specific to the FX3 firmware.
Build BSP after setting up Nios system

We need lms_spi_controller/mem_init/meminit.qip to build the
FPGA successfully, so this needs to be created prior to anything
else happening.
Merge pull request #13 from rtucker/bladerf

Build BSP after setting up Nios system
hdl: Added README for better building instructions.
Fix typo in timing constraints config
Merge pull request #14 from rtucker/bladerf

Fix typo in timing constraints config
hdl: Fix a little typo.
fx3: Fixed a URL typo.
libbladeRF: Fixed 'make install' target to copy symlinks correctly.

The copy previously was dereferencing symlinks, resulting in
copies of the library being installed. Asides from being terribly
undesirable, this also resulted in ldconfig warnings.