ARM: OMAP4+: Reset CPU1 properly for kexec

We need to reset CPU1 properly for kexec when booting different
kernel versions. Otherwise CPU1 will attempt to boot the the
previous kernel's start_secondary(). Note that the restctrl
register is different from the low-power mode wakeup register
CPU1_WAKEUP_NS_PA_ADDR. We need to configure both.

Let's fix the issue by defining SoC specific data to initialize
things in a more generic way. And let's also standardize omap-smp.c
to use soc_is instead of cpu_is while at it.

Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Tested-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>