soc: qcom: glink_ssr: Internalize ssr_notifiers

Rather than carrying a special purpose blocking notifier for glink_ssr
in remoteproc's qcom_common.c, move it into glink_ssr so allow wider
reuse of the common one.

The rpmsg glink header file is used in preparation for the next patch.

Acked-by: Chris Lew <clew@codeaurora.org>
Acked-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Link: https://lore.kernel.org/r/20200423003736.2027371-3-bjorn.andersson@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

include/linux/rpmsg/qcom_glink.h

@@ -26,4 +26,10 @@ static inline void qcom_glink_smem_unregister(struct qcom_glink *glink) {}
 
 #endif
 
+#if IS_ENABLED(CONFIG_RPMSG_QCOM_GLINK_SSR)
+void qcom_glink_ssr_notify(const char *ssr_name);
+#else
+static inline void qcom_glink_ssr_notify(const char *ssr_name) {}
+#endif
+
 #endif