ima: fix showing large 'violations' or 'runtime_measurements_count'

ima: fix showing large 'violations' or 'runtime_measurements_count'

BugLink: https://bugs.launchpad.net/bugs/1836802
commit 1e4c8dafbb6bf72fb5eca035b861e39c5896c2b7 upstream.

The 12 character temporary buffer is not necessarily long enough to hold
a 'long' value.  Increase it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>