This patch adds ioctl for the LEB unmap operation (as a debugging
option so far).

[Re-named ioctl to make it look the same as the other one and made
 some minor stylistic changes. Artem Bityutskiy.]
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>