Fix lintian warning about bash-completion shebangs

Lintian warns using a shebang in a bash-completion script. While I don't
think they do any particular harm, it is redundant.

Author: waveform80

pinctrl/pinctrl-completion.bash

@@ -1,4 +1,3 @@
-#!/usr/bin/env bash
 _pinctrl ()
 {
     local cur prev words cword split cmd pins pincomp ALLPINS CHIPS chip pinmode=false prefix arg i func pull;