ARM: keystone2: Switch to using the poweroff command

Now that we have a standard way to power off the hardware, switch to
using that rather than our own command.

Cc: Vitaly Andrianov <vitalya@ti.com>
Cc: Nishanth Menon <nm@ti.com>
Cc: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-keystone/Makefile b/arch/arm/mach-keystone/Makefile
index 7f12009..8829e7f 100644
--- a/arch/arm/mach-keystone/Makefile
+++ b/arch/arm/mach-keystone/Makefile
@@ -12,6 +12,7 @@
 ifndef CONFIG_SPL_BUILD
 obj-y	+= cmd_clock.o
 obj-y	+= cmd_mon.o
+obj-y	+= cmd_poweroff.o
 endif
 obj-y	+= msmc.o
 obj-y	+= ddr3.o cmd_ddr3.o