With recently introduced dualroot CoT for SPs where they are owned
either by SiP or by Platform. SiP owned SPs index starts at SP_PKG1_ID
while Plat owned SPs index starts at SP_PKG5_ID.

This patch modifies SP makefile generator script to take CoT as an
argument and if it is "dualroot" then generates SP_PKG in order
mentioned above, otherwise generates it sequentially.

Signed-off-by: Ruari Phipps <ruari.phipps@arm.com>
Change-Id: Iffad1131787be650a9462f6f8cc09b603cddb3b8