malta: add harddisk support

Is it possible to backport commit r46269 (3c298f89-4303-0410-b956-a3cf2f4a3e73) to CC 15.05 in order to provide harddisk support.

Backporting tested (info available at: https://forum.openwrt.org/viewtopic.php?id=62389).

Thnx in advance!

Here is the original patch from trunk:
>From 76bfcd46bd55263947461e40bd02047922755c72 Mon Sep 17 00:00:00 2001
From: blogic <blogic@3c298f89-4303-0410-b956-a3cf2f4a3e73>
Date: Wed, 8 Jul 2015 14:25:36 +0000
Subject: [PATCH] malta: add harddisk support

works with:
qemu-system-mipsel -M malta \
-hda openwrt-malta-le-root.ext4 \
-kernel openwrt-malta-le-vmlinux.elf \
-nographic -append "root=/dev/sda console=ttyS0"

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/chaos_calmer@48666 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/linux/malta/config-3.18

@@ -7,6 +7,8 @@ CONFIG_ARCH_MIGHT_HAVE_PC_PARPORT=y
 CONFIG_ARCH_MIGHT_HAVE_PC_SERIO=y
 CONFIG_ARCH_WANT_IPC_PARSE_VERSION=y
 # CONFIG_AX88796_93CX6 is not set
+CONFIG_ATA=y
+CONFIG_ATA_PIIX=y
 CONFIG_BLK_DEV_BSG=y
 CONFIG_BLK_DEV_BSGLIB=y
 # CONFIG_BLK_DEV_DM is not set
@@ -15,6 +17,7 @@ CONFIG_BLK_DEV_BSGLIB=y
 CONFIG_BLK_DEV_RAM=y
 CONFIG_BLK_DEV_RAM_COUNT=16
 CONFIG_BLK_DEV_RAM_SIZE=4096
+CONFIG_BLK_DEV_SD=y
 CONFIG_BOARD_SCACHE=y
 CONFIG_BOOT_ELF32=y
 CONFIG_BOUNCE=y
@@ -52,6 +55,7 @@ CONFIG_DNOTIFY=y
 CONFIG_DUMMY_CONSOLE=y
 CONFIG_EARLY_PRINTK=y
 CONFIG_ENABLE_MUST_CHECK=y
+CONFIG_EXT4_FS=y
 CONFIG_FIRMWARE_IN_KERNEL=y
 CONFIG_FS_POSIX_ACL=y
 CONFIG_GENERIC_ATOMIC64=y