Fix misspellings of "system", "controller", "interrupt" and "necessary".

Fix the various misspellings of "system", controller", "interrupt" and
"[un]necessary".

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 2e4eae5..5886147 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -126,7 +126,7 @@
 	else
 		subsystem = kobject_name(&kset->kobj);
 	if (!subsystem) {
-		pr_debug("unset subsytem caused the event to drop!\n");
+		pr_debug("unset subsystem caused the event to drop!\n");
 		return 0;
 	}