uhd: Increase MC-BTS FPGA clock rate to 51.2 MHz

Addresses following issues where UHD 3.9 and likely other UHD versions
would report a master clock (FPGA) rate error. Update MC-BTS FPGA clock
for B200 and B210 to 51.2 MHz, which is supported by all UHD versions.
Only B200/B210 is supported for MC-BTS operation.

https://osmocom.org/issues/1963
https://osmocom.org/issues/1648

ALERT UHDDevice.cpp:548:set_master_clk: Failed to set master clock rate
ALERT UHDDevice.cpp:549:set_master_clk: Requested clock rate 3.2e+06
ALERT UHDDevice.cpp:550:set_master_clk: Actual clock rate 5e+06

Change-Id: I78fb2c0959abd0e666628ba39f433162aafb067e
1 file changed