soc: qcom: smem: Correct stubbed API dependency

The Shared Memory driver API stubs depend on CONFIG_MSM_SMD being defined,
but SMD is a client of SMEM, so it is improper for any part of SMEM to
depend on SMD.  Instead the stubs should depend on CONFIG_MSM_SMEM.

Correct the dependency.

Change-Id: I65667964d6228e5cdec4625015eebd56825ae2e1
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>