arch/arm, arch/powerpc: add # of SEC engines on the SOC

Some SOCs, specifically the ones in the C29x familiy can have
multiple security engines. This patch adds a system configuration
define which indicates the maximum number of SEC engines that
can be found on a SoC.

Signed-off-by: Alex Porosanu <alexandru.porosanu@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>