x86/mm: Make use of the default access param from xc_altp2m_create_view

x86/mm: Make use of the default access param from xc_altp2m_create_view

At this moment the default_access param from xc_altp2m_create_view is
not used.

This patch assigns default_access to p2m->default_access at the time of
initializing a new altp2m view.

Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>
Reviewed-by: Petre Pircalabu <ppircalabu@bitdefender.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>