usb: fix CONFIG_SYS_MPC83xx_USB_ADDR not defined error

fix a stray CONFIG_MPC83XX that escaped commit
0f898604.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Remy Bohmer <linux@bohmer.net>

include/usb/ehci-fsl.h

@@ -85,7 +85,7 @@
 #define MPC83XX_SCCR_USB_DRCM_01	0x00100000
 #define MPC83XX_SCCR_USB_DRCM_10	0x00200000
 
-#if defined(CONFIG_MPC83XX)
+#if defined(CONFIG_MPC83xx)
 #define CONFIG_SYS_MPC8xxx_USB_ADDR CONFIG_SYS_MPC83xx_USB_ADDR
 #elif defined(CONFIG_MPC85xx)
 #define CONFIG_SYS_MPC8xxx_USB_ADDR CONFIG_SYS_MPC85xx_USB_ADDR