csky/vdso: Use generic union vdso_data_store

There is already a generic union definition for vdso_data_store in the vdso
datapage header.

Use this definition to prevent code duplication.
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20240219153939.75719-11-anna-maria@linutronix.de

arch/csky/kernel/vdso.c

@@ -15,14 +15,8 @@ extern char vdso_start[], vdso_end[];
 static unsigned int vdso_pages;
 static struct page **vdso_pagelist;
 
-/*
- * The vDSO data page.
- */
-static union {
-	struct vdso_data	data;
-	u8			page[PAGE_SIZE];
-} vdso_data_store __page_aligned_data;
-struct vdso_data *vdso_data = &vdso_data_store.data;
+static union vdso_data_store vdso_data_store __page_aligned_data;
+struct vdso_data *vdso_data = vdso_data_store.data;
 
 static int __init vdso_init(void)
 {