wil6210: change reply_size arg to u16 in wmi_call

Change the type of the argument reply_size from u8 to
u16 in order to support reply sizes > 255 bytes.
The driver already supports u16 reply size in all
other places, this was the only missing change.

Signed-off-by: Lior David <liord@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>