[msm7630] Bug fix to not overwrite r3 value when checking for halcyon v1

We check for halcyon v1 we use r3; same register is used later to pass
on cache settings.  Use r4 instead when checking for processor version
so we dont overwrite the cache setting value in r3.

Change-Id: I22430f0bb766b49ee0431f0a6b7fe413fc23ca56
1 file changed