KVM: arm64: Move PROTECTED_NVHE_STACKTRACE around

Make the dependency with EL2_DEBUG more obvious by moving the
stacktrace configurtion *after* it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-2-maz@kernel.org