selftests: check percentage range for memory-hotplug test

selftests: check percentage range for memory-hotplug test

BugLink: http://bugs.launchpad.net/bugs/1710868
Check the precentage range for -r flag in memory-hotplug test.

Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
(cherry picked from commit 72441ea5886780d04ac96913e02dba9e84ea80e5)
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>