[PATCH] swsusp: simpler calculation of number of pages in PBE list

The function calc_nr uses an iterative algorithm to calculate the number of
pages needed for the image and the pagedir.  Exactly the same result can be
obtained with a one-line expression.

Note that this was even proved correct ;-).

Signed-off-by: Michal Schmidt <xschmi00@stud.feec.vutbr.cz>
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>