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 <amit.pundir@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>