fix(scmi): make msg_header variable volatile

When tf-a is built with the llvm toolchain, the compiler optimizes the
variable in some way which results in SCMI_MSG_GET_TOKEN assert failure
in multiple places. This patch makes the msg_header variable in
mailbox_mem struct volatile, which seems to fix the issue.

Signed-off-by: sahil <>
Change-Id: I1d28b30a6472fc23ed85adff9cf73dfb536e39cc
1 file changed