ARM: keystone2: move address space switch printk into generic code

There is no point platform code doing this, let's move it into the
generic code so it doesn't get duplicated.

Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>