Staging: comedi: s526: fixes for pulse generator

Some changes and corrections to handling of
INSN_CONFIG_GPCT_SINGLE_PULSE_GENERATOR, and
INSN_CONFIG_GPCT_PULSE_TRAIN_GENERATOR, so they interpret insn->data[]
as per the comments in the code.

Signed-off-by: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>