parisc: Drop homebrewn io[read|write]64_[lo_hi|hi_lo]
The parisc implements ioread64_lo_hi(), ioread64_hi_lo()
iowrite64_lo_hi() and iowrite64_hi_lo() while we already
have a perfectly working generic version in the generic
portable assembly in <linux/io-64-nonatomic-hi-lo.h>.
Drop the custom versions in favor for the defaults.