VMCI: Fix possible memcpy() run-time warning in vmci_datagram_invoke_guest_handler()

VMCI: Fix possible memcpy() run-time warning in vmci_datagram_invoke_guest_handler()

The changes are similar to those given in the commit 19b070fefd0d
("VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()").

Fix filling of the msg and msg_payload in dg_info struct, which prevents a
possible "detected field-spanning write" of memcpy warning that is issued
by the tracking mechanism __fortify_memcpy_chk.

Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org>
Link: https://lore.kernel.org/r/20240219105315.76955-1-kovalev@altlinux.org
Signed-off-by: Kees Cook <keescook@chromium.org>