Fix use before set bug in arm32 guest.

I accidentally set the unwind register object using the uninitialized
arm registers. Actually set using the arm registers that contains
valid data.

Test: All unit tests pass.
Test: Ran on an arm32 guest host and verified the guest unwind is valid.
Change-Id: I20a2b6675648df1c627af80aa708071109bdf099
1 file changed