Memory leaks can happen in the vc_resize() function in drivers/char/vt.c
because of the vc->vc_screenbuf variable overriding in vc_allocate().  The
kmemleak reported trace is as follows:

  <__kmalloc>
  <vc_resize>
  <fbcon_init>
  <visual_init>
  <vc_allocate>
  <con_open>
  <tty_open>
  <chrdev_open>

This patch no longer allocates a screen buffer in vc_allocate() if it was
already allocated by vc_resize().
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>