wlcore: change way of checking the firmware version

The firmwares version string contain 5 integers.  We used to consider
all the digits (except for the first one, which indicates the chip) as
linearly increasing version numbers.  This is not correct, because
some of the integers indicate type of firmware (eg. single-role
vs. multi-role) or the internal project it was created for.

Besides, this varies a bit from chip to chip, so we need to make the
firmware version checks more flexible (eg. allow the lower driver to
ignore some of the integers).  Additionally, we need to change the
code so that we only check for a linearly increasing number on the
fields where this actually makes sense.

Signed-off-by: Luciano Coelho <coelho@ti.com>