target/hppa: Implement Fast TLB Insert instructions

These instructions are present on pcxl and pcxl2 machines,
and are used by NetBSD and OpenBSD.  See

     https://parisc.wiki.kernel.org/images-parisc/a/a9/Pcxl2_ers.pdf


     page 13-9 (195/206)

Signed-off-by: Nick Hudson <skrll@netbsd.org>
Message-Id: <20190423063621.8203-2-nick.hudson@gmx.co.uk>
[rth: Use extending loads, locally managed temporaries.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>