pcmcia/yenta: add module parameter for O2 speedups

O2-bridges can do read prefetch and write burst. However, for some combinations
of older bridges and cards, this causes problems, so it is disabled for those
bridges. Now, as some users know their setup works with the speedups enabled, a
new parameter is introduced to the driver. Now, a user can specifically enable
or disable these features, while the default is what we have today: detect the
bridge and decide accordingly. Fixes Bugzilla entry 15014.

Simplify and unify the printouts, fix a whitespace issue while we are here.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Tested-by:  <frodone@gmail.com>
[linux@dominikbrodowski.net: whitespace fixes]
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>