When jumping back into the kernel to code that knows that it would be
using HSRR registers instead of SRR registers, we need to make sure we
pass it all information on where to jump to in HSRR registers.
Unfortunately, we used r10 to store the information to distinguish between
the HSRR and SRR case. That register got clobbered in between though,
rendering the later comparison invalid.
Instead, let's use cr1 to store this information. That way we don't
need yet another register and everyone's happy.