[PARISC] Disable use of fpregs in pa_memcpy

Disable use of fpregs in pa_memcpy, and turn on the
-mdisable-fpregs flag.

Signed-off-by: Randolph Chung <tausq@parisc-linux.org>

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