mailbox: qcom-ipcc: Enable loading QCOM_IPCC as a module

This patch enables the qcom_ipcc driver to be loaded as a
module. IPCC is fairly core to system, so as such it should
never be unloaded. It registers as a mailbox + irq controller
and the irq controller drivers in kernel are not supposed to
be unloaded as they don't have the visibility over the clients
consuming the irqs. Hence adding supress_bind_attrs to disable
bind/unbind via sysfs.

Signed-off-by: Amit Pundir <[e-mail]>
Reviewed-by: Manivannan Sadhasivam <[e-mail]>
Signed-off-by: Jassi Brar <[e-mail]>

drivers/mailbox/Kconfig

···
 	  you want to build the Spreatrum mailbox controller driver.
 
 config QCOM_IPCC
-	bool "Qualcomm Technologies, Inc. IPCC driver"
+	tristate "Qualcomm Technologies, Inc. IPCC driver"
 	depends on ARCH_QCOM || COMPILE_TEST
 	help
 	  Qualcomm Technologies, Inc. Inter-Processor Communication Controller

drivers/mailbox/qcom-ipcc.c

···
 	.driver = {
 		.name = "qcom-ipcc",
 		.of_match_table = qcom_ipcc_of_match,
+		.suppress_bind_attrs = true,
 	},
 };