ipw2100/ipw2200: note firmware loading caveat in Kconfig help text

Most wireless drivers load their firmware at interface open time, which
generally occurs after the filesystem is available. However, the ipw drivers
load their firmware at probe time because firmware is required to read the
device MAC address. When built-in, probe happens before the filesystem is
available, hence device init will only complete successfully if the user
has made special arrangements (including firmware plus a loader in the
initramfs).

Note all this in the kconfig help text for both drivers.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>