ARM: pxa: fix invalid mfp pin issue

Failure is reported on hx4700 with kernel v3.3-rc1.

__mfp_validate: GPIO20 is invalid pin
__mfp_validate: GPIO21 is invalid pin
__mfp_validate: GPIO15 is invalid pin
__mfp_validate: GPIO78 is invalid pin
__mfp_validate: GPIO79 is invalid pin
__mfp_validate: GPIO80 is invalid pin
__mfp_validate: GPIO33 is invalid pin
__mfp_validate: GPIO48 is invalid pin
__mfp_validate: GPIO49 is invalid pin
__mfp_validate: GPIO50 is invalid pin

Since pxa_last_gpio is used in mfp-pxa2xx driver. But it's only
updated in pxa-gpio driver that run after mfp-pxa2xx driver.

So update the pxa_last_gpio first in mfp-pxa2xx driver.
Reported-by: Paul Parsons <lost.distance@yahoo.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>

arch/arm/mach-pxa/mfp-pxa2xx.c

@@ -226,6 +226,12 @@ static void __init pxa25x_mfp_init(void)
 {
 	int i;
 
+	/* running before pxa_gpio_probe() */
+#ifdef CONFIG_CPU_PXA26x
+	pxa_last_gpio = 89;
+#else
+	pxa_last_gpio = 84;
+#endif
 	for (i = 0; i <= pxa_last_gpio; i++)
 		gpio_desc[i].valid = 1;
 
@@ -295,6 +301,7 @@ static void __init pxa27x_mfp_init(void)
 {
 	int i, gpio;
 
+	pxa_last_gpio = 120;	/* running before pxa_gpio_probe() */
 	for (i = 0; i <= pxa_last_gpio; i++) {
 		/* skip GPIO2, 5, 6, 7, 8, they are not
 		 * valid pins allow configuration