update_kernel: Simplify name for temp rootfs mountpoint

We currently try to strip away ${FLAGS_rootfs} from the beginning of
${FLAGS_device}, but it's possible that these two variables won't have
any common prefix. Let's just use some other name, like 'rootfs_mounted'
to indicate the mounted location for the rootfs we want to update so we
don't have to worry about these two variables being similar.

This allows me to update the kernel to a DUT's onboard storage when the
device is booted off a USB stick (/dev/sda) and the onboard storage is
something else like EMMC (/dev/mmcblk0p).

TEST=Update kernel to DUT while running from USB stick

Change-Id: I58462d2183f2640341960d88a10a24415ff339a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2002777
Tested-by: Stephen Boyd <swboyd@chromium.org>
Auto-Submit: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
1 file changed