BabyWR: GTH termination for REF_CLK
Termination by R58 may not be the proper solution since IBUFDS_GTE4 is internally biased and terminated. R58 to GND violated the DC bias.
Solution: Remove R58 and increase R13 from 27 ohm to 56 ohm.
See also Ref_Clk_GTH_Termination.pdf