Cleanup: fix "MHz" spelling

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/drivers/usb/usbdcore_mpc8xx.c b/drivers/usb/usbdcore_mpc8xx.c
index fa02003..53bde0d 100644
--- a/drivers/usb/usbdcore_mpc8xx.c
+++ b/drivers/usb/usbdcore_mpc8xx.c
@@ -1227,7 +1227,7 @@
 		return;
 	}
 
-	/* Assume the brgclk is 'good enough', we want !(gd->cpu_clk%48Mhz)
+	/* Assume the brgclk is 'good enough', we want !(gd->cpu_clk%48MHz)
 	 * but, can /probably/ live with close-ish alternative rates.
 	 */
 	divisor = (gd->cpu_clk / 48000000L) - 1;