[sh4] Fix build (broken since r159346).
https://bugs.webkit.org/show_bug.cgi?id=124455

Patch by Julien Brianceau <jbriance@cisco.com> on 2013-11-16
Reviewed by Oliver Hunt.

Fix LLINT implementation for sh4 architecture to handle properly load and store operations with pr register.

* offlineasm/sh4.rb:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@159381 268f45cc-cd09-0410-ab3c-d52691b4dbfc