parisc: fix fallocate syscall

fallocate(off_t) gets redirected by glibc to fallocate64(loff_t)
where the 64bit loff_t values get splitted into two 32bit (hi/lo)
values. This patch fixes this syscall for the 32- and 64bit kernel.

Signed-off-by: Helge Deller <deller@gmx.de>