arm64: Use larger stacks when KASAN is selected

AddressSanitizer instrumentation can significantly bloat the stack, and
with GCC 7 this can result in stack overflows at boot time in some
configurations.

We can avoid this by doubling our stack size when KASAN is in use, as is
already done on x86 (and has been since KASAN was introduced).
Regardless of other patches to decrease KASAN's stack utilization,
kernels built with KASAN will always require more stack space than those
built without, and we should take this into account.

Change-Id: I3da9bea59c6f3580bfe15d1b2d1f2a208a9a0401
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: b02faed15d86f846b0f23f47b92e0782baa873ed
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>