ver_linux: use 'udevadm', instead of 'udevinfo'

'udevinfo' no longer seems to be available across various
distros. 'udevadm' seems to be the currently valid way to look up the
'udev' version.

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

Rely on regex to find the version number, rather than rely on numerical input to be found in a particular input field.
Proposed implementation also eliminates the necessity to invoke 'grep' + 'awk'.

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