torture: Provide EXPERT Kconfig option for arm64 KCSAN torture.sh runs

torture: Provide EXPERT Kconfig option for arm64 KCSAN torture.sh runs

The arm64 architecture requires that KCSAN-enabled kernels be built with
the CONFIG_EXPERT=y Kconfig option.  This commit therefore causes the
torture.sh script to provide this option, but only for --kcsan runs on
arm64 systems.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <kasan-dev@googlegroups.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>