staging: comedi: drivers: cleanup cmd->flags use

Most of the comedi drivers that support async commands have some sort
of timer to control the acquisition timing. For these drivers, Step 4
of the (*do_cmdtest) operations calls a ns_to_timer() function that
converts the desired ns time of the command into a value used to set
the timer. These ns_to_timer() functions also typically pass the
cmd->flags in order to determine the desired rounding mode.

Some of the drivers mask the cmd->flags with TRIG_ROUND_MASK when
calling the ns_to_timer() functions. Move all the masking into the
ns_to_timer() functions and just pass the cmd->flags directly.

The cmd->flags member is an unsigned int, change the parameter type
in the the ns_to_timer() functions to match.

For aesthetics, rename the parameter in all the ns_to_timer()
functions to 'flags'.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>