onewire_parser: Make step changes pass glitch detection

onewire_parser: Make step changes pass glitch detection

The glitch detection code does not recognize step changes at
all. Currently it re-reads the temperature values until maximum glitch
threshold (two reads) and then just uses the last data. This is not
ideal on noisy lines as the last data might be a glitch itself.

Improve the logic so that after considering for a glitch, we compare
two consequent readings and see if the delta between those two is less
than the glitch threshold. If it is less, we consider the data
good. This is needed in case the temperature is changing quickly and
we don't get two identical values, but almost same.

Signed-off-by: Timo Kokkonen <timo.t.kokkonen@iki.fi>