The current rounding of "size" is wrong:

 - If "start" is sufficiently near the next page boundary, "size"
   is decremented by more than enough and the last page is lost.

 - If "size" is sufficiently small, it is wrapped around and gets
   a bogus value.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>