Cleanup: fix "MHz" spelling

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/cpu/ppc4xx/4xx_pci.c b/cpu/ppc4xx/4xx_pci.c
index eca92e8..e8871fc 100644
--- a/cpu/ppc4xx/4xx_pci.c
+++ b/cpu/ppc4xx/4xx_pci.c
@@ -286,7 +286,7 @@
 #endif /* CONFIG_SYS_PCI_CLASSCODE */
 
 	/*--------------------------------------------------------------------------+
-	 * If PCI speed = 66Mhz, set 66Mhz capable bit.
+	 * If PCI speed = 66MHz, set 66MHz capable bit.
 	 *--------------------------------------------------------------------------*/
 	if (bd->bi_pci_busfreq >= 66000000) {
 		pci_read_config_word(PCIDEVID_405GP, PCI_STATUS, &temp_short);