mpc85xx: Fix the offset of register address error

The offset of register address within GPIO module is just
CONFIG_SYS_MPC85xx_GPIO_ADDR. So, fix it. The following platforms
are confirmed: MPC8572, P1023, P1020, P1022, P2020, P4080,
P5020, P5040, T4240, B4860.

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>

arch/powerpc/include/asm/mpc85xx_gpio.h

@@ -20,7 +20,7 @@
 static inline void mpc85xx_gpio_set(unsigned int mask,
 		unsigned int dir, unsigned int val)
 {
-	ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR + 0xc00);
+	ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR);
 
 	/* First mask off the unwanted parts of "dir" and "val" */
 	dir &= mask;
@@ -56,7 +56,7 @@ static inline void mpc85xx_gpio_set_high(unsigned int gpios)
 
 static inline unsigned int mpc85xx_gpio_get(unsigned int mask)
 {
-	ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR + 0xc00);
+	ccsr_gpio_t *gpio = (void *)(CONFIG_SYS_MPC85xx_GPIO_ADDR);
 
 	/* Read the requested values */
 	return in_be32(&gpio->gpdat) & mask;