ARM: 7846/1: Update SMP_ON_UP code to detect A9MPCore with 1 CPU devices

The generic code is well equipped to differentiate between
SMP and UP configurations.However, there are some devices which
use Cortex-A9 MP core IP with 1 CPU as configuration. To let
these SOCs to co-exist in a CONFIG_SMP=y build by leveraging
the SMP_ON_UP support, we need to additionally check the
number the cores in Cortex-A9 MPCore configuration. Without
such a check in place, the startup code tries to execute
ALT_SMP() set of instructions which lead to CPU faults.

The issue was spotted on TI's Aegis device and this patch
makes now the device work with omap2plus_defconfig which
enables SMP by default. The change is kept limited to only
Cortex-A9 MPCore detection code.

Note that if any future SoC *does* use 0x0 as the PERIPH_BASE, then
the SCU address check code needs to be #ifdef'd for for the Aegis
platform.

Acked-by: Sricharan R <r.sricharan@ti.com>
Signed-off-by: Vaibhav Bedia <vaibhav.bedia@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>