staging: comedi: vmk80xx: cleanup pwm subdevice init

Change the 'pwm_bits' in the boardinfo to 'pwm_maxdata' so that the
calculation of s->maxdata can be removed. Also, change the type to
match the comedi_subdevice type. For aesthetic reasons, rename the
'pwm_chans' boardinfo and change its type also.

Remove the '0' values in the boardinfo.

Rename the (*insn_read) and (*insn_write) functions for the pwm
subdevice to make grepping easier.

For aesthetic reasons, add some whitespace to the subdevice init.

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