uhd: set receive gain during initialization

This shouldn't matter much, but the gain settings through the
interface are short circuited right now, which makes this a
problem.

Signed-off-by: Thomas Tsou <ttsou@vt.edu>

git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@2639 19bc5d8c-e614-43d4-8b26-e1612bc8e597

Transceiver52M/UHDDevice.cpp

@@ -315,6 +315,7 @@ bool uhd_device::open()
 
 	// Set gains to midpoint
 	set_usrp_tx_gain(usrp_dev, 0.0);
+	set_usrp_rx_gain(usrp_dev, 0.0);
 
 	// Set reference clock
 	set_usrp_ref_clk(usrp_dev, use_ext_ref);