ver_linux: sh-utils, look for numerical input, not field number

Rely on regex to find the version number, rather than rely on numerical input to be found in a particular input field.

Tested on:
Gentoo Linux
Debian 6.0.10
Oracle Linux Server release 7.1

Signed-off-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>