mwifiex: fix bug for wildcard-prefix wowlan pattern

Wildcard prefix bytes are ignored while downloading packet
pattern to firmware. As packet offset is not adjusted
accordingly firmware end up matching the pattern at wrong
offset. The packet offset is corrected in this patch.

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>