use common channel group allocation/release code

use common channel group allocation/release code

Eliminate individual open coded alloc and release code for channel
groups in hardware drivers and input modules. Use common code instead.

This commit affects: arachnid-labs-re-load-pro, atten-pps3xxx,
baylibre-acme, dcttech-usbrelay, demo, dreamsourcelab-dslogic, fx2lafw,
gwinstek-gds-800, gwinstek-gpd, hameg-hmo, hantek-4032l, hantek-6xxx,
hantek-dso, hp-3457a, hp-59306a, hung-chang-dso-2100, itech-it8500,
lecroy-xstream, maynuo-m97, microchip-pickit2, motech-lps-30x, rigol-dg,
rigol-ds, scpi-pps, siglent-sds, yokogawa-dlm, input/vcd.