x86/p2m: fix p2m_finish_type_change()

x86/p2m: fix p2m_finish_type_change()

finish_type_change() returns a negative int on error, but the
current code checks if ( !rc ). We also need to treat
finish_type_change()'s return codes cumulatively in the
success case (don't overwrite a 1 returned while processing
the hostp2m if processing an altp2m returns 0).

The breakage was introduced by commit 0fb4b58c8b
("x86/altp2m: fix display frozen when switching to a new view
early").

Properly indent the out: label while at it.

Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>