parisc: Remove unused symbol vdso_data

The symbol vdso_data is and has been unused.
Remove it.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-2-13a4669dfc8c@linutronix.de

Author: t-8ch

arch/parisc/include/asm/vdso.h

@@ -12,8 +12,6 @@
 #define VDSO64_SYMBOL(tsk, name) ((tsk)->mm->context.vdso_base + (vdso64_offset_##name))
 #define VDSO32_SYMBOL(tsk, name) ((tsk)->mm->context.vdso_base + (vdso32_offset_##name))
 
-extern struct vdso_data *vdso_data;
-
 #endif /* __ASSEMBLY __ */
 
 /* Default link addresses for the vDSOs */