arch: arm64: Depend on SMP being disabled for single threading

Disabling multithreading is not possible when enabling SMP (logically)
so depend on SMP being disabled to enable
ARCH_HAS_SINGLE_THREAD_SUPPORT.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

Author: carlescufi

arch/arm64/core/Kconfig

@@ -9,7 +9,7 @@ config CPU_CORTEX_A
 	select HAS_FLASH_LOAD_OFFSET
 	select SCHED_IPI_SUPPORTED if SMP
 	select CPU_HAS_FPU
-	select ARCH_HAS_SINGLE_THREAD_SUPPORT
+	select ARCH_HAS_SINGLE_THREAD_SUPPORT if !SMP
 	select CPU_HAS_DCACHE
 	select CPU_HAS_ICACHE
 	imply FPU