brcm63xx: fix compilation on 3.14

Fixes the following issue:

drivers/gpio/gpio-bcm63xx.c: In function 'bcm63xx_gpio_probe':
drivers/gpio/gpio-bcm63xx.c:80:4: error: implicit declaration of function 'devm_kasprintf' [-Werror=implicit-function-declaration]

Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 44986

target/linux/brcm63xx/patches-3.14/374-gpio-add-a-simple-GPIO-driver-for-bcm63xx.patch

@@ -121,7 +121,7 @@ Signed-off-by: Jonas Gorski <jogo@openwrt.org>
 +		u32 ngpios;
 +
 +		if (id >= 0)
-+			bgc->gc.label = devm_kasprintf(dev, GFP_KERNEL,
++			bgc->gc.label = kasprintf(GFP_KERNEL,
 +						       "bcm63xx-gpio.%d", id);
 +
 +		if (!of_property_read_u32(dev->of_node, "ngpios", &ngpios))