mips32_pracc: jump to 0xff20.0200 if cpu reads wrong addr

mips32_pracc: jump to 0xff20.0200 if cpu reads wrong addr

On some CPUs, like bcm7401 with EJTAG v2.0 we can have situation where
CPU do not stops execution. For example, all CP0 commands will have this issue.
In this case we should some hove recover our session. Currently
jump to 0xff20.0200 seems to be good option. If it brake some thing on
newer EJTAG, then check for EJTAG v2.0 should be added.

Change-Id: Icd8841f38a1a85e0f7682b6dc358af8dfaae0744
Signed-off-by: Oleksij Rempel <bug-track@fisher-privat.net>
Reviewed-on: http://openocd.zylin.com/1353
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>