denver: use plat_my_core_pos() to get core position

The current functions to disable and enable Dynamic Code Optimizer
(DCO) assume that all denver cores are in the same cluster. They
ignore AFF1 field of the mpidr_el1 register, which leads to
incorect logical core id calculation.

This patch calls the platform handler, plat_my_core_pos(), to get
the logical core id to disable/enable DCO for the core.

Original change by: Krishna Sitaraman <ksitaraman@nvidia.com>

Change-Id: I45fbd1f1eb032cc1db677a4fdecc554548b4a830
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>