We shouldn't assume we can set tcr_el1.ips to 42 bits. Set
it based on what we read from id_aa64mmfr0_el1. Didn't see
a problem, but might as well be correct.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>