media: cec: core: add glitch error injection

media: cec: core: add glitch error injection

This adds support for inserting 'glitches' after a falling and/or
rising edge. This tests what happens when there are little voltage
spikes after falling or rising edges, which can be caused due to
noise or reflections on the CEC line.

A proper CEC implementation will deglitch this, but a poor implementation
can create a Low Drive pulse in response, effectively making CEC unusable.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>