staging: comedi: c6xdigio: add readback of last pwm channel values
staging: comedi: c6xdigio: add readback of last pwm channel values

Add and (*insn_read) for the PWM subdevice to allow reading back the
last value written to the channels.

There are only 2 PWM channels and they have a maxdata of 500. Pack
the last values in the subdevice 'state' instead of adding a private
data struct to this driver.

Signed-off-by: H Hartley Sweeten <382ff55d8e07d1082d179e669636cd1552da4f36@visionengravers.com>
Reviewed-by: Ian Abbott <9e6ba6483b6a3e14d61f7c987e72ecb5b46122d6@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs