parisc: Drop __init from map_pages declaration

With huge kernel pages, we randomly eat a SPARC in map_pages(). This
is fixed by dropping __init from the declaration.

However, map_pages references the __init routine memblock_alloc_try_nid
via memblock_alloc.  Thus, it needs to be marked with __ref.

memblock_alloc is only called before the kernel text is set to readonly.

The __ref on free_initmem is no longer needed.

Comment regarding map_pages being in the init section is removed.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Helge Deller <deller@gmx.de>