soc: qcom: rpmhpd: Allow RPMHPD driver to be loaded as a module

This patch allow the rpmhpd driver to be loaded as a permenent
module. Meaning it can be loaded from a module, but then cannot
be unloaded.

Ideally, it would include a remove hook and related logic, but
apparently the genpd code isn't able to track usage and cleaning
things up?

So making it a permenent module at least improves things slightly
over requiring it to be a built in driver.

Cc: Todd Kjos <[e-mail]>
Cc: Saravana Kannan <[e-mail]>
Cc: Andy Gross <[e-mail]>
Cc: Bjorn Andersson <[e-mail]>
Cc: Rajendra Nayak <[e-mail]>
Cc: [e-mail]
Acked-by: Saravana Kannan <[e-mail]>
Tested-by: Bjorn Andersson <[e-mail]>
Reviewed-by: Bjorn Andersson <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bjorn Andersson <[e-mail]>

drivers/soc/qcom/Kconfig

···
 	  help apply the aggregated state on the resource.
 
 config QCOM_RPMHPD
-	bool "Qualcomm RPMh Power domain driver"
+	tristate "Qualcomm RPMh Power domain driver"
 	depends on QCOM_RPMH && QCOM_COMMAND_DB
 	help
 	  QCOM RPMh Power domain driver to support power-domains with

drivers/soc/qcom/rpmhpd.c

···
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/pm_domain.h>
 #include <linux/slab.h>
···
 	{ .compatible = "qcom,sm8150-rpmhpd", .data = &sm8150_desc },
 	{ }
 };
+MODULE_DEVICE_TABLE(of, rpmhpd_match_table);
 
 static int rpmhpd_send_corner(struct rpmhpd *pd, int state,
 			      unsigned int corner, bool sync)
···
 	return platform_driver_register(&rpmhpd_driver);
 }
 core_initcall(rpmhpd_init);
+
+MODULE_DESCRIPTION("Qualcomm Technologies, Inc. RPMh Power Domain Driver");
+MODULE_LICENSE("GPL v2");