Use full include paths like it is done for common includes.

This cleanup was started in commit d40e0e08283a ("Sanitise includes
across codebase"), but it only cleaned common files and drivers. This
patch does the same to Arm platforms.

Change-Id: If982e6450bbe84dceb56d464e282bcf5d6d9ab9b
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>