configs/raspberrypi_defconfig: configure eth0 through dhcp

The rpi board has an ethernet port, so configure it at startup.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/raspberrypi_defconfig

@@ -3,6 +3,7 @@ BR2_arm1176jzf_s=y
 BR2_ARM_EABIHF=y
 
 BR2_TARGET_GENERIC_GETTY_PORT="tty1"
+BR2_SYSTEM_DHCP="eth0"
 
 # Linux headers same as kernel, a 4.1 series
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_1=y