sparc64: Reduce TLB flushes during hugepte changes

sparc64: Reduce TLB flushes during hugepte changes

During hugepage map/unmap, TSB and TLB flushes are currently
issued at every PAGE_SIZE'd boundary which is unnecessary.
We now issue the flush at REAL_HPAGE_SIZE boundaries only.

Without this patch workloads which unmap a large hugepage
backed VMA region get CPU lockups due to excessive TLB
flush calls.

Orabug: 23071722

Signed-off-by: Nitin Gupta <nitin.m.gupta@oracle.com>
(cherry picked from commit b42a694198cca38e8cdb3f601266bf591ba3291d)
(cherry picked from commit fdc7f39ae632a9ec0114c59090131d2db7dd7682)
Signed-off-by: Allen Pais <allen.pais@oracle.com>