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/ide/pci/siimage.c b/drivers/ide/pci/siimage.c
index 689786d..1353afb 100644
--- a/drivers/ide/pci/siimage.c
+++ b/drivers/ide/pci/siimage.c
@@ -26,7 +26,7 @@
  *
  *	If you have strange problems with nVidia chipset systems please
  *	see the SI support documentation and update your system BIOS
- *	if neccessary
+ *	if necessary
  *
  *  The Dell DRAC4 has some interesting features including effectively hot
  *  unplugging/replugging the virtual CD interface when the DRAC is reset.