gmc-mh-1x-2x: Cosmetics, whitespace, cleanups.
gmc-mh-1x-2x: Fix two compiler warnings.
gmc-mh-1x-2x: Use 'di' variable to match other drivers.
gmc-mh-1x-2x: Don't put driver-specific things in sr/SR namespace.
gmc-mh-1x-2x: Use standard API callback names for now.

If multiple functions need to be differentiated later, we can bring
back more specific names.
appa-55ii: Minor cosmetics, whitespace fixes.
teleinfo: Minor cleanups.
Centralise duplicated logging helper defines.
log prefixes: Cosmetics, consistency fixes, typo fixes.
rigol-ds: Rename and document some confusingly named variables.
rigol-ds: Use rigol_ds_channel_start() function for legacy protocol too.
rigol-ds: Unify code for counting expected incoming bytes.
rigol-ds: Unify partial read handling.