improve code readability in adc-recorder.c
improve code readability in adc-recorder.c

pavel-demin/red-pitaya-notes,pavel-demin/red-pitaya-notes,fbalakirev/red-pitaya-notes,pavel-demin/red-pitaya-notes,fbalakirev/red-pitaya-notes,fbalakirev/red-pitaya-notes,fbalakirev/red-pitaya-notes,pavel-demin/red-pitaya-notes,pavel-demin/red-pitaya-notes,fbalakirev/red-pitaya-notes,fbalakirev/red-pitaya-notes,pavel-demin/red-pitaya-notes,fbalakirev/red-pitaya-notes,pavel-demin/red-pitaya-notes,pavel-demin/red-pitaya-notes