KVM: PPC: e500: Track TLB1 entries with a bitmap

Rather than invalidate everything when a TLB1 entry needs to be
taken down, keep track of which host TLB1 entries are used for
a given guest TLB1 entry, and invalidate just those entries.

Based on code from Ashish Kalra <Ashish.Kalra@freescale.com>
and Liu Yu <yu.liu@freescale.com>.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>