wifi: libertas: fix code style in Marvell structs

Several of the structs are using the deprecated convention of items[1]
for a dynamically sized trailing element. Convert these structs to the
modern C99 style of items[]. Also fix a couple of camel case struct
element names.

Signed-off-by: Doug Brown <doug@schmorgal.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230123053132.30710-2-doug@schmorgal.com