mm/page_alloc: Drop the deferred printing

For rt kernel, the console printing occurs either atomically or from
the printing kthread, all the printk defer functions have been dropped
by commit 25f13bd1 ("printk: remove deferred printing"). This patch
drops the new one which is introduced by stable commit 0431e132


("mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock").

Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Li Wang <li.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>