ARM: shmobile: armadillo800eva: enable rw rootfs mount

armadillo800eva default boot loader is "hermit",
and it's tag->u.core.flags has flag when kernel boots.
Because of this, ${LINUX}/arch/arm/kernel/setup.c :: parse_tag_core()
didn't remove MS_RDONLY flag from root_mountflags.
Thus, the rootfs is mounted as "readonly".
This patch adds "rw" kernel parameter,
and enable read/write mounts for rootfs

Cc: Masahiro Nakai <nakai@atmark-techno.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

arch/arm/configs/armadillo800eva_defconfig

@@ -33,7 +33,7 @@ CONFIG_AEABI=y
 CONFIG_FORCE_MAX_ZONEORDER=13
 CONFIG_ZBOOT_ROM_TEXT=0x0
 CONFIG_ZBOOT_ROM_BSS=0x0
-CONFIG_CMDLINE="console=tty0 console=ttySC1,115200 earlyprintk=sh-sci.1,115200 ignore_loglevel root=/dev/nfs ip=dhcp nfsroot=,rsize=4096,wsize=4096"
+CONFIG_CMDLINE="console=tty0 console=ttySC1,115200 earlyprintk=sh-sci.1,115200 ignore_loglevel root=/dev/nfs ip=dhcp nfsroot=,rsize=4096,wsize=4096 rw"
 CONFIG_CMDLINE_FORCE=y
 CONFIG_KEXEC=y
 CONFIG_VFP=y