Tegra: memctrl_v2: remove weakly defined TZDRAM setup handler

This patch removes the per-platform, weakly defined TZDRAM setup handler,
as all affected platforms implement the actual handler.

Change-Id: I95d04b2a771bc5d673e56b097d45c493fa388ee8
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>