fix(xlat_tables_v2): zeromem to clear all tables

This patch replaces the for loops to sero individual tables or entries
in the translation table context with zeromem to improve the boot time.

On Tegra platforms, this patch has proved to save 10ms during boot.

Signed-off-by: Bhavesh Parekh <bparekh@nvidia.com>
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: Iea9fb2c18ae7a1aef4fe42c4151a321fb3f8660e
1 file changed