libs/guest: Fix resource leaks in xc_core_arch_map_p2m_tree_rw()

libs/guest: Fix resource leaks in xc_core_arch_map_p2m_tree_rw()

Edwin, with the help of GCC's -fanalyzer, identified that p2m_frame_list_list
gets leaked.  What fanalyzer can't see is that the live_p2m_frame_list_list
and live_p2m_frame_list foreign mappings are leaked too.

Rework the logic so the out path is executed unconditionally, which cleans up
all the intermediate allocations/mappings appropriately.

Fixes: bd7a29c3d0b9 ("tools/libs/ctrl: fix xc_core_arch_map_p2m() to support linear p2m table")
Reported-by: Edwin Török <edwin.torok@cloud.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>