Fix lazy mode vmalloc synchronization for paravirt

Touching vmalloc memory in the middle of a lazy mode update can generate
a kernel PDE update, which must be flushed immediately.  The fix is to
leave lazy mode when doing a vmalloc sync.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>