migration: Rename normal to normal_pages

Rest of counters that refer to pages has a _pages suffix.
And historically, this showed the number of full pages transferred.
The name "normal" refered to the fact that they were sent without any
optimization (compression, xbzrle, zero_page, ...).

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
3 files changed