remoteproc: qcom: q6v5-mss: Sync MSS with RMTFS QMI service

Introduce RMTFS qmi lookup client to synchronize bring up/down modem with the REMOTE FS QMI service.

---
The currently implemented workaround in the Linaro QCOMLT releases is to blacklist the qcom_q6v5_pil kernel module and load this explicitly after rmtfs has been started.

With this patch the modem module can be loaded automatically by the platform_bus and will only be booted as the rmtfs becomes available. Performing actions such as upgrading (and restarting) the rmtfs service will cause the modem to automatically restart and hence continue to function after the upgrade.

v3:
Move rmtfs lookup client to the q6v5_mss driver [Suggested-by: Bjorn Andersson <[email protected]>] [Suggested-by: Brian Norris <[email protected]>] Add deny_sysfs_ops flag to prevent updation of state/firmware [Suggested-by: Bjorn Andersson <[email protected]>]

v2:
Remove rproc_boot/shutdown from rmtfs_mem open/release and add qmi lookup for Remote file system service to address Brian's race concerns.

Depends on: https://patchwork.kernel.org/patch/10601325/

 drivers/remoteproc/Kconfig         |  1 +
 drivers/remoteproc/qcom_q6v5_mss.c | 41 ++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

index 8894935583e2..5919098697ec 100644
@@ -100,6 +100,7 @@ config QCOM_Q6V5_MSS
 	depends on RPMSG_QCOM_GLINK_SMEM || RPMSG_QCOM_GLINK_SMEM=n
 	depends on QCOM_SYSMON || QCOM_SYSMON=n
 	select MFD_SYSCON
+	select QCOM_QMI_HELPERS
 	select QCOM_Q6V5_COMMON
 	select QCOM_RPROC_COMMON
 	select QCOM_SCM

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