staging: comedi: dmm32at: fix style issues

Before:
      1 ERROR: code indent should use tabs where possible
      1 WARNING: please, no spaces at the start of a line

After:
  (none)
Signed-off-by: David Decotigny <ddecotig@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>