[PATCH] Don't try to pivot to new ramfs if already running on one

[PATCH] Don't try to pivot to new ramfs if already running on one
This patch allows the luci-flash script to continue with the upgrade if
openwrt is already running on a ramfs. This allows the use of luci-flash
as an _installer_ when running from an iso image. A user could boot the
system from a bootable cd and write an image to the hard disk or CF from
the Flash Firmware page.

Signed-off-by: Vasilis Tsiligiannis <b_tsiligiannis@silverton.gr>