Add new field in MemoryInfo to get advertised memory size.

This API will get the advertised memory size from the bootloader parameter
passed to the kernel. The advertised memory size might be different from
the MemTotal value in /proc/meminfo. This could be due the original design
manufacturer (ODM) reserved part of the memory for the Trusted Execution
Environment.

Test: Run test caes
Bug: 231718727
Change-Id: I06494cb9013048d73a83f2180a9241c2259d46eb