x86: vdso: Fix build with older gcc

x86: vdso: Fix build with older gcc

gcc-4.4.4:

arch/x86/vdso/vma.c: In function 'vgetcpu_cpu_init':
arch/x86/vdso/vma.c:247: error: unknown field 'limit0' specified in initializer
arch/x86/vdso/vma.c:247: warning: missing braces around initializer
arch/x86/vdso/vma.c:247: warning: (near initialization for '(anonymous).<anonymous>')
arch/x86/vdso/vma.c:248: error: unknown field 'limit' specified in initializer
arch/x86/vdso/vma.c:248: warning: excess elements in struct initializer
arch/x86/vdso/vma.c:248: warning: (near initialization for '(anonymous)')
....

I couldn't find any way of tricking it into accepting an initializer
format :(

Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Fixes: 258801563b ("x86/vdso: Change the PER_CPU segment to use struct desc_struct")
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>