ARM: dts: msm: Increase virtual memory for secure context bank for msm8996

Increase the virtual memory size of the secure bitstream context bank
from 300MB to 600MB along with the virtual map to 4GB from 3.5GB. Earlier
limits were set for legacy reasons which are not applicable anymore.

Change-Id: I743cf72a381124cf1c1aca2024bf4b25bdadb677
Signed-off-by: Shivaprasad Hongal <shongal@codeaurora.org>
Signed-off-by: Shalaj Jain <shalajj@codeaurora.org>