Tegra: aarch64: calculate core position from one place
Tegra: aarch64: calculate core position from one place

This patch updates 'plat_my_core_pos' handler to call
'plat_core_pos_from_mpidr' instead of implementing the same logic
at two places.

Change-Id: I1e56adaa10dc2fe3440e5507e0e260d8932e6657
Signed-off-by: Kalyani Chidambaram <867f319f492b092f09933284a30504d604729758@nvidia.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware