libxc: duplicate snippet to allocate p2m_host array

libxc: duplicate snippet to allocate p2m_host array

Currently all in tree code doesn't set the superpage flag, I would just
remove superpage support if I can, but Konrad wants it retained for the
moment.

As I'm going to change the p2m_host array allocation, duplicate the code
snippet to allocate p2m_host array in this patch, so that we retain the
behaviour in superpage case.

This patch introduces no functional change and it will make future patch
easier to review. Also removed one stray tab while I was there.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>