BACKPORT: FROMLIST: arm64: vdso: disable Shadow Call Stack

Shadow stacks are only available in the kernel, so disable SCS
instrumentation for the vDSO.

Bug: 145210207
Change-Id: I6e01b2c7788ba52d3b754b1fbd5bfb908b45741b
(am from https://lore.kernel.org/patchwork/patch/1149061/

)
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>