fsi: core: register with postcore_initcall

When testing an i2c driver that is a fsi bus driver, I saw the following
oops:

 kernel BUG at drivers/base/driver.c:153!
 Internal error: Oops - BUG: 0 [#1] ARM

 [<8027cb1c>] (driver_register) from [<80344e88>] (fsi_driver_register+0x2c/0x38)
 [<80344e88>] (fsi_driver_register) from [<805f5ebc>] (fsi_i2c_driver_init+0x1c/0x24)
 [<805f5ebc>] (fsi_i2c_driver_init) from [<805d1f14>] (do_one_initcall+0xb4/0x170)
 [<805d1f14>] (do_one_initcall) from [<805d20f0>] (kernel_init_freeable+0x120/0x1dc)
 [<805d20f0>] (kernel_init_freeable) from [<8043f4a8>] (kernel_init+0x18/0x104)
 [<8043f4a8>] (kernel_init) from [<8000a5e8>] (ret_from_fork+0x14/0x2c)

This is because the fsi bus had not been registered. This fix registers the bus
with postcore_initcall instead, to ensure it is registered earlier on.

When the fsi core is used as a module this should not be a problem as the fsi
driver will depend on the fsi bus type symbol, and will therefore load the core
before the driver.

Fixes: 0508ad1fff11 ("drivers/fsi: Add empty fsi bus definitions")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fsi/fsi-core.c

@@ -883,17 +883,16 @@ struct bus_type fsi_bus_type = {
 };
 EXPORT_SYMBOL_GPL(fsi_bus_type);
 
-static int fsi_init(void)
+static int __init fsi_init(void)
 {
 	return bus_register(&fsi_bus_type);
 }
+postcore_initcall(fsi_init);
 
 static void fsi_exit(void)
 {
 	bus_unregister(&fsi_bus_type);
 }
-
-module_init(fsi_init);
 module_exit(fsi_exit);
 module_param(discard_errors, int, 0664);
 MODULE_LICENSE("GPL");