ARM: dts: Amend tz usage table with the proper buffer types

Trustzone memory usage numbers are -
SECURE BIT-STREAM - 1
SECURE PIXEL      - 2
SECURE NON-PIXEL  - 3

Amend the tz-usage table buffer types matching with
the supported partition buffer types of iommu secure
BIT-STREAM/PIXEL/NON-PIXEL domains.

Change-Id: Iebf37bbb6bca5c457f28c016e95a5ec4eadb084c
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>