e1d: Remove bogus vty_show function.
e1d: Remove bogus vty_show function.

It's optional for an input driver to provide this function, and e.g.
mISDN doesn't provide it, either.

Change-Id: I56ed4244121f2019ece80d15bd07d5a8ce958273

osmocom/libosmo-abis,osmocom/libosmo-abis,osmocom/libosmo-abis