Prevent BSS from being cleared twice on BookE

[int0dster_gmail.com]

Summary

First time BSS is cleared in booke_init(), Second time it cleared in powerpc_init().
Any variable initialized between two those guys gets wiped out what is wrong. In particular
it wipes tlb1_entries initialized by tlb1_init()

Test Plan

Build and boot the kernel

[jhibbits]

Great! This was another leftover from the statically cached tlb1, where we would re initialize then reset the tlb. Since we no longer reset the tlb this zeroing is no longer needed, and is instead potentially harmful.