Revert "arm64: Stash shadow stack pointer in the task struct on interrupt"

This reverts commit 3f225f29 which is
commit 59b37fe5 upstream.

It breaks some test systems, so obviously the backport to 5.10.y wasn't
quite correct :(

Revert it for now until this can be figured out better.

Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1071c357225a8b41f15767a27b5c56cf94d7a5f7