ARMV7: Vexpress: Add missing MMC header

Add a header file with the missing function prototype to fix

ca9x4_ct_vxp.c: In function 'cpu_mmc_init':
ca9x4_ct_vxp.c:93: warning: implicit declaration of function 'arm_pl180_mmci_init'

introduced by commit "ARMV7: Vexpress: Add MMC support"
(f0c64526)

Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>
CC: Andy Fleming <afleming@freescale.com>
CC: Matt Waddel <matt.waddel@linaro.org>

board/armltd/vexpress/ca9x4_ct_vxp.c

@@ -38,6 +38,7 @@
 #include <asm/arch/systimer.h>
 #include <asm/arch/sysctrl.h>
 #include <asm/arch/wdt.h>
+#include "../drivers/mmc/arm_pl180_mmci.h"
 
 static ulong timestamp;
 static ulong lastdec;