x86: Change some CR0 settings when setting up kvm x86 processes.

x86: Change some CR0 settings when setting up kvm x86 processes.

These values were (seemingly) arbitrarily changed from the original,
non-KVM settings, and no longer matched the comments which were also
copied over. These two bits enable alignment checking on memory accesses
(not normally used on x86), and whether kernel code can write to read
only pages.

Change-Id: I48e560e448e4849607f12e9336d1ab0458ad9407
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/38536
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>