ARM: keystone: dts: add psci command definition

ARM: keystone: dts: add psci command definition

This commit adds definition for cpu_on, cpu_off and cpu_suspend
commands.  These definitions must match the corresponding PSCI
definitions in boot monitor.

Having those command and corresponding PSCI support in boot monitor
allows run time CPU hot plugin.

Link: http://lkml.kernel.org/r/E1b8koV-0004Hf-2j@rmk-PC.armlinux.org.uk
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>