[PATCH] powerpc: Prevent unsigned wrap in htab_dt_scan_page_sizes()

[Paul Mackerras]

Roel Kluin writes:

> Check to prevent unsigned wrap of size before subtraction.
> 
> Signed-off-by: Roel Kluin <roel.kluin at gmail.com>
> ---
> Is this maybe better or are we certain that size can't wrap?

Patch looks good, though while you're at it, you could add a space
after the "while".

Acked-by: Paul Mackerras <paulus at samba.org>