e2fsprogs: remove findfs option

The e2fsprogs package's findfs option provides no capabilities. When the
option is selected, a symbolic link is generated from findfs to e2label;
however, e2label will not handle findfs since the respective code is
explicitly disabled when `--disable-libblkid` is passed in. At this
time, the e2fsprogs package only supports findfs capabilities when
building its "private blkid library".

Note that the `--disable-libblkid` configuration argument must remain
to prevent conflicts with util-linux's libblkid and an e2fsprogs-
generated variant (see e1ffc2f7).

Since e2fsprogs cannot provide findfs capabilities, the option is being
removed in this change. A following change will be introduced to include
util-linux's findfs utility.

Signed-off-by: James Knight <james.knight@rockwellcollins.com>
Cc: Zheng Yi <yzheng@techyauld.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>