MIPS: Make init_vdso a subsys_initcall.

Quoting from Jiri Slaby's patch of a similar nature for x86:

    When initrd is in use and a driver does request_module() in its
    module_init (i.e. __initcall or device_initcall), a modprobe
    process is created with VDSO mapping. But VDSO is inited even in
    __initcall, i.e. on the same level (at the same time), so it may
    not be inited yet (link order matters).

Move init_vdso up to subsys_initcall to avoid the issue.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Patchwork: http://patchwork.linux-mips.org/patch/1386/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/vdso.c

@@ -63,7 +63,7 @@ static int __init init_vdso(void)
 
 	return 0;
 }
-device_initcall(init_vdso);
+subsys_initcall(init_vdso);
 
 static unsigned long vdso_addr(unsigned long start)
 {