Fix off-by-1 error in RAM migration code

Fix off-by-1 error in RAM migration code

The code for migrating (or savevm-ing) memory pages starts off by creating
a dirty bitmap and filling it with 1s.  Except, actually, because bit
addresses are 0-based it fills every bit except bit 0 with 1s and puts an
extra 1 beyond the end of the bitmap, potentially corrupting unrelated
memory.  Oops.  This patch fixes it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit 7ec81e56edc2b2007ce0ae3982aa5c18af9546ab)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>