ARM: OMAP: make iommu subsys_initcall to fix builtin omap3isp

omap3isp depends on omap's iommu and will fail to probe if
initialized before it (which always happen if they are builtin).

Make omap's iommu subsys_initcall as an interim solution until
the probe deferral mechanism is merged.

Reported-by: James <[e-mail]>
Debugged-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Ohad Ben-Cohen <[e-mail]>
Cc: stable <[e-mail]>
Cc: Tony Lindgren <[e-mail]>
Cc: Hiroshi Doyu <[e-mail]>
Cc: Joerg Roedel <[e-mail]>
Signed-off-by: Joerg Roedel <[e-mail]>

arch/arm/mach-omap2/mailbox.c

···
 	platform_driver_unregister(&omap2_mbox_driver);
 }
 
-module_init(omap2_mbox_init);
+/* must be ready before omap3isp is probed */
+subsys_initcall(omap2_mbox_init);
 module_exit(omap2_mbox_exit);
 
 MODULE_LICENSE("GPL v2");

drivers/iommu/omap-iommu.c

···
 
 	return platform_driver_register(&omap_iommu_driver);
 }
-module_init(omap_iommu_init);
+/* must be ready before omap3isp is probed */
+subsys_initcall(omap_iommu_init);
 
 static void __exit omap_iommu_exit(void)
 {