Match the data type of a temporary holding a reference to the FIFO port
with the type of the original reference coming from `struct parport',
avoiding data truncation with LP64 ports such as SPARC64 that refer to
PCI port I/O locations via their corresponding MMIO addresses and will
therefore have non-zero bits in the high 32-bit part of the reference.
And in any case it is cleaner to have the data types matching here.