Fix for BMIPS

Fix for BMIPS

BMIPS always needs 2 additional instructions to reach the core.
Seems there is a 2 instructions fifo between the tap and the core, or it behaves in this way.
No idea of the purpose of this fifo, I can only guess.
Of course function mips32_pracc_clean_text_jump() must add this additional instructions (NOPs).
Only tested on bcm3348..

Change-Id: I3183d3ce865d469d7262ba4b15446e5743a5f1df
Signed-off-by: Salvador Arroyo <salvador@telecable.es>
Reviewed-on: http://openocd.zylin.com/2270
Tested-by: jenkins
Reviewed-by: Kent Brinkley <jkbrinkley.imgtec@gmail.com>
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>