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/drivers/ata/pata_radisys.c b/drivers/ata/pata_radisys.c
index d5b7649..8109b08 100644
--- a/drivers/ata/pata_radisys.c
+++ b/drivers/ata/pata_radisys.c
@@ -161,7 +161,7 @@
  *
  *	Called when the libata layer is about to issue a command. We wrap
  *	this interface so that we can load the correct ATA timings if
- *	neccessary. Our logic also clears TIME0/TIME1 for the other device so
+ *	necessary. Our logic also clears TIME0/TIME1 for the other device so
  *	that, even if we get this wrong, cycles to the other device will
  *	be made PIO0.
  */