staging: comedi: drivers: re-do macros for PLX PCI 9080 LASxRR values

Rename the macros for the PLX PCI 9080 LAS0RR and LAS1RR registers in
"plx9080.h", using the prefix `PLX_LASRR_`.  Make use of the `BIT(x)`
and `GENMASK(h,l)` macros to define the values.

Define a macro `PLX_LASRR_PREFETCH` for the "prefetchable memory" bit in
this register, and define a macro `PLX_LASRR_MLOC_MASK` to mask the PCI
memory location control bits.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>