Transceiver52M: Remove support for ancient libusrp versions

Current functionality with these old versions is questionable.
There is no reason to use any version of GNU Radio / libusrp older
than 3.3. Version 3.4.2 is the only recommended version for USRP1
users.

Non-USRP1 users must use UHD driver from Ettus Research.

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