staging: comedi: amplc_dio200.h: rename 'has_enhancements' in boardinfo

This member of the boardinfor is only set for the PCIE boards. For
aeshetics, rename it to 'is_pcie'.

For clarity, use this flag in the (*auto_attach) to determine if the
dio200_pcie_board_setup() function needs to be called instead of using
the switch (context_model).

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>