cmds/boot/localboot: fix cannot find mount dir error
cmds/boot/localboot: fix cannot find mount dir error

After commit 686c9d2, we need to MkdirAll the mount point ahead of time

Signed-off-by: Shelly Chang <e1938762eae535b67a9df6350ff421787a2d8431@wiwynn.com>

u-root/u-root,u-root/u-root,u-root/u-root