systemd: parameterise wallpaper.service

Remove all invocations of 'feh' for setting wallpaper that are now
redundant as this service should handle setting the wallpaper in all
relevant situations.

Signed-off-by: Joe Groocock <me@frebib.net>

scripts/4screens

@@ -10,5 +10,3 @@ xrandr --output $BOTTOM_LEFT --primary --mode 1920x1080 --pos 0x1080 --rotate no
        --output $TOP_LEFT --mode 1920x1080 --pos 0x0 --rotate inverted \
        --output $TOP_RIGHT --mode 1920x1080 --pos 1920x0 --rotate inverted \
        --output $BOTTOM_RIGHT --mode 1920x1080 --pos 1920x1080 --rotate normal
-
-feh --no-fehbg --no-xinerama --bg-fill $DOTFILES/lakesidesunrise.jpg

scripts/dock-displays

@@ -15,5 +15,3 @@ MODENAME=${MODELINE%% *}
 xrandr --newmode $MODELINE 2>/dev/null || true
 xrandr --addmode $OUTPUT $MODENAME 2>/dev/null || true
 xrandr --output  $OUTPUT --mode $MODENAME
-
-feh --no-fehbg --no-xinerama --bg-fill $DOTFILES/lakesidesunrise.jpg