kernel, esp32: Add SMP kconfig flag and MP_NUM_CPUS variable

Simply define the Kconfig variables in this patch so they can be used
in later patches.  Define MP_NUM_CPUS correctly on esp32.  No code
changes.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>

arch/xtensa/soc/esp32/Kconfig.defconfig

@@ -15,4 +15,7 @@ config IRQ_OFFLOAD_INTNUM
 config XTENSA_ASM2
 	def_bool y
 
+config MP_NUM_CPUS
+	default 2
+
 endif

kernel/Kconfig

@@ -561,6 +561,22 @@ config USE_SWITCH
 	architecture provides both, _arch_switch incurs more somewhat
 	overhead and may be slower.
 
+config SMP
+	bool
+	prompt "Enable symmetric multithreading support"
+	default n
+	help
+	When true, Zephyr will be build with SMP support, allowing
+	more than one CPU to schedule Zephyr tasks at a time.
+
+config MP_NUM_CPUS
+	int
+	prompt "Number of CPUs/cores"
+	default 1
+	help
+	Number of multiprocessing-capable cores available to the
+	multicpu API and SMP features.
+
 source "kernel/Kconfig.event_logger"
 
 source "kernel/Kconfig.power_mgmt"