firmware: Add support for querying msmc memory

firmware: Add support for querying msmc memory

DMSC can use certain amount of msmc memory available in the
system. Also certain part of msmc memory can be marked as L3
cache using board config. But users might not know what size
is being used and the remaining available msmc memory. In order
to fix this TISCI protocol provides a messages that can query
the available msmc memory in the system. Add support for this
message.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>