ARM: dts: msm: Set max non secure region to 0xE0000000 on msm8998

Video hardware on msm8998 chipset limits the max non secure region
address to 0xE0000000. So reduce non secure region size to 0x6f800000
from 0x8f800000 to limit the max address to 0xE0000000.

CRs-Fixed: 1092881
Change-Id: Ib9602aa2298caf01ab01b4e0225c112c71bb81f4
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>