fix(drivers/scmi-msg): entry: add weak functions

One platform may not implement all the protocols, to avoid build break
when we not include all the protocols, add weak functions.

Reviewed-by: Jacky Bai <ping.bai@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Change-Id: I1485baa2e8f381cb0eede1a7b93ed10e49934971
1 file changed