[PARISC] Remove obsolete _hlt cruft

Remove a bunch of obsolete code from process.c, these routines were
likely imported from the i386 version of process.c when the port
started. The routines are only used in floppy.c, which I seriously
doubt will ever work on parisc, due to architectural assumptions.

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>