rtlwifi: make a couple arrays larger

This is a static checker fix.  "cal_num" is 10.  We're declaring the
tx_dt[] and rx_td[] arrays as 3 element arrays.  The static checker
complains that we do:

	tx_dt[cal] = (vdf_y[1]>>20)-(vdf_y[0]>>20);

"cal" is the iterator and it is in the 0-9 range so it looks like
we could corrupt memory.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>