e2fsprogs: removed 'sed -u' option

e2fsprogs: removed 'sed -u' option

In embedded box, sed might be provided another providers like Busybox,
hence use generic options whenever possible.
/bin/sed -> /etc/alternatives/sed
/etc/alternatives/sed -> /bin/busybox.nosuid

Here used 'sed -u' option is not necessary, hence removed it.

Fixes below error:
sed: invalid option -- 'u'

Also added 'set -eux' option which halts execution of the script
on any failures.

Signed-off-by: Aditya Tayade <Aditya.Tayade@kpit.com>
Signed-off-by: Pawan Badganchi <Pawan.Badganchi@kpit.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>