omap4: Add smc API to read AuxCoreBoot0 register

This patch adds a secure API to read AuxCoreBoot0 register to
check the cpu boot status. It also moves the other smc APIs
to common omap44xx-smc.S. This APIs should not be marked as
__INIT because we need these to be present for CPU hotplug

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>