Clarify c_sdp_W_gn_id = 5.

...isturb2_unb2b_station/src/vhdl/disturb2_unb2b_station.vhd

...2_unb2b_sdp_station/src/vhdl/lofar2_unb2b_sdp_station.vhd

...2_unb2c_sdp_station/src/vhdl/lofar2_unb2c_sdp_station.vhd