mtd: host variant needs host-util-linux, host-e2fsprogs

Since mtd was converted to the package infrastructure in commit
de4cf4e9 ("mtd: convert to gentargets,
add host package"), its host variant depended on host-e2fsprogs. At
the time, only a host variant of the mtd package was available.

When a target variant of mtd was introduced in commit
b50e0fa1 ("mtd: add option to build
mkfs.ubifs for target"), it depended on util-linux.

So today, the target variant continues to depend on util-linux, while
the host variant depends on e2fsprogs. What mkfs.ubifs really needs
is libuuid, which is provided by util-linux. It was in fact provided
by the fact that host-e2fsprogs depends on host-util-linux.

But really, host-e2fsprogs is not needed as a dependency, so use
host-util-linux to be consistent with the target variant.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>