fix(plat/arm): fix SP count limit without dual root CoT

Remove reserved range for platform provider owned SPs if the dual root
CoT is disabled and allow SPs to populate the range up to MAX_SP_IDS.

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: Ib4ec18f6530d2515ada21d2c0c388d55aa479d26
1 file changed