TransceiverUHD: Add transceiver support for UHD devices

Supported devices includes USRP N200/N210/USRP2, B200/B210, X300/X310.
Other Ettus devices are not supported due to bandwidth limitations.
There is no direct embedded device support at this time.

The UHD transceiver device operating rate is fixed at 6.25 Msps, which
interfaces with the UMTS chip rate of 3.84 Mcps through a combined
polyphase resampling and RRC pulse-shaping filterbank. The effective
oversampling factor is approximate 1.63 samples per symbol.

Tested against Agilent 89600 VSA for appropriate EVM and ACP values.

Signed-off-by: Tom Tsou <tom@tsou.cc>
TransceiverUHD: Configure UHD build when driver is detected

Setup configure to build and install the UHD transceiver if the UHD
driver is found. Otherwise, build the RAD1 transceiver. For UHD
transceiver, perform CPU checking for Intel SSE capability. Update
CPU check macros from GNU Autoconf Archive version 2014.10.15.

Signed-off-by: Tom Tsou <tom@tsou.cc>