Cleanup: fix "MHz" spelling

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/cpu/ppc4xx/speed.c b/cpu/ppc4xx/speed.c
index d21bd82..ed6e55b 100644
--- a/cpu/ppc4xx/speed.c
+++ b/cpu/ppc4xx/speed.c
@@ -148,7 +148,7 @@
 		 * is equal to the 405GP SYS_CLK_FREQ. If not in bypass mode, check VCO
 		 * to make sure it is within the proper range.
 		 *    spec:    VCO = SYS_CLOCK x FBKDIV x PLBDIV x FWDDIV
-		 * Note freqVCO is calculated in Mhz to avoid errors introduced by rounding.
+		 * Note freqVCO is calculated in MHz to avoid errors introduced by rounding.
 		 */
 		if (sysInfo->pllFwdDiv == 1) {
 			sysInfo->freqProcessor = CONFIG_SYS_CLK_FREQ;