MIPS: AR7: Fix GPIO register size for Titan variant.

The 'size' variable contains the correct register size for both AR7
and Titan, but we never used it to ioremap the correct register size.
This problem only shows up on Titan.

[ralf@linux-mips.org: Fixed the fix.  The original patch as in patchwork
recognizes the problem correctly then fails to fix it ...]
Reported-by: NAlexander Clouter <alex@digriz.org.uk>
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Patchwork: https://patchwork.linux-mips.org/patch/2380/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/ar7/gpio.c

@@ -325,9 +325,7 @@ int __init ar7_gpio_init(void)
 		size = 0x1f;
 	}
 
-	gpch->regs = ioremap_nocache(AR7_REGS_GPIO,
-					AR7_REGS_GPIO + 0x10);
-
+	gpch->regs = ioremap_nocache(AR7_REGS_GPIO, size);
 	if (!gpch->regs) {
 		printk(KERN_ERR "%s: failed to ioremap regs\n",
 					gpch->chip.label);