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: 25880156 ("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>

arch/x86/vdso/vma.c

@@ -230,7 +230,7 @@ __setup("vdso=", vdso_setup);
 static void vgetcpu_cpu_init(void *arg)
 {
 	int cpu = smp_processor_id();
-	struct desc_struct d;
+	struct desc_struct d = { };
 	unsigned long node = 0;
 #ifdef CONFIG_NUMA
 	node = cpu_to_node(cpu);
@@ -243,15 +243,13 @@ static void vgetcpu_cpu_init(void *arg)
 	 * quickly in user space in vgetcpu. (12 bits for the CPU
 	 * and 8 bits for the node)
 	 */
-	d = (struct desc_struct) {
-		.limit0 = cpu | ((node & 0xf) << 12),
-		.limit = node >> 4,
-		.type = 5,		/* RO data, expand down, accessed */
-		.dpl = 3,		/* Visible to user code */
-		.s = 1,			/* Not a system segment */
-		.p = 1,			/* Present */
-		.d = 1,			/* 32-bit */
-	};
+	d.limit0 = cpu | ((node & 0xf) << 12);
+	d.limit = node >> 4;
+	d.type = 5;		/* RO data, expand down, accessed */
+	d.dpl = 3;		/* Visible to user code */
+	d.s = 1;		/* Not a system segment */
+	d.p = 1;		/* Present */
+	d.d = 1;		/* 32-bit */
 
 	write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
 }