linux-firmware: adjust Config.in text for mwifiex

With SD, USB and PCI-E variants available for several chips,
bus-prefixed entries get mis-aligned badly.
Rearrange them to use bus-suffixes instead.

Config options and the files themselves remain bus-prefixed.

Signed-off-by: Alex Suykov <alex.suykov@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>