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/arch/sh64/kernel/pci_sh5.c b/arch/sh64/kernel/pci_sh5.c
index 388bb71..b4d9534 100644
--- a/arch/sh64/kernel/pci_sh5.c
+++ b/arch/sh64/kernel/pci_sh5.c
@@ -480,7 +480,7 @@
                 return -EINVAL;
         }
 
-	/* The pci subsytem needs to know where memory is and how much
+	/* The pci subsystem needs to know where memory is and how much
 	 * of it there is. I've simply made these globals. A better mechanism
 	 * is probably needed.
 	 */