srmcons: fix kmalloc(GFP_KERNEL) inside spinlock

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=8341



Cc: <matthias.kaehlcke@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>