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/spi/mpc52xx_psc_spi.c b/drivers/spi/mpc52xx_psc_spi.c
index e9aba93..7051e6c 100644
--- a/drivers/spi/mpc52xx_psc_spi.c
+++ b/drivers/spi/mpc52xx_psc_spi.c
@@ -181,7 +181,7 @@
 		}
 
 
-		/* enable interupts and wait for wake up
+		/* enable interrupts and wait for wake up
 		 * if just one byte is expected the Rx FIFO genererates no
 		 * FFULL interrupt, so activate the RxRDY interrupt
 		 */