riscv: 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>
Link: https://lore.kernel.org/r/20240220085212.6547-1-anna-maria@linutronix.de

arch/riscv/kernel/vdso.c

@@ -30,14 +30,8 @@ enum rv_vdso_map {
 
 #define VVAR_SIZE  (VVAR_NR_PAGES << PAGE_SHIFT)
 
-/*
- * 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;
 
 struct __vdso_info {
 	const char *name;