arch-x86, arch-power: fix calls to bits and insertBits

arch-x86, arch-power: fix calls to bits and insertBits

The bits and insertBits assume the first bit is the larger bit and the last
bit is the smaller bit.  This commit fixes several X86 and Power calls to
these functions that incorrectly assumed that first was the smaller bit.

Change-Id: I2b5354d1b9ca66e3436c4a72042416a6ce6dec01
Reviewed-on: https://gem5-review.googlesource.com/10241
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>