mx6: add support of multi-processor command

This allows u-boot to load different OS or Bare Metal application on
different cores of the i.MX6 SoC.
For example: running Android on cpu0 and a RT OS like QNX/FreeRTOS on cpu1.

Signed-off-by: Gabriel Huau <contact@huau-gabriel.fr>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/cpu/armv7/mx6/soc.c b/arch/arm/cpu/armv7/mx6/soc.c
index f2dee76..ac84a1f 100644
--- a/arch/arm/cpu/armv7/mx6/soc.c
+++ b/arch/arm/cpu/armv7/mx6/soc.c
@@ -35,6 +35,12 @@
 	u32	fpga_rev;
 };
 
+u32 get_nr_cpus(void)
+{
+	struct scu_regs *scu = (struct scu_regs *)SCU_BASE_ADDR;
+	return readl(&scu->config) & 3;
+}
+
 u32 get_cpu_rev(void)
 {
 	struct anatop_regs *anatop = (struct anatop_regs *)ANATOP_BASE_ADDR;