ARM: shmobile: defconfig: enable initrd

Enable initrd support.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
[horms+renesas@verge.net.au: dropped enabling atag dtb compat]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/configs/shmobile_defconfig

@@ -3,6 +3,7 @@ CONFIG_NO_HZ=y
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
 CONFIG_LOG_BUF_SHIFT=16
+CONFIG_BLK_DEV_INITRD=y
 CONFIG_CC_OPTIMIZE_FOR_SIZE=y
 CONFIG_SYSCTL_SYSCALL=y
 CONFIG_EMBEDDED=y