ath6kl: Remove modparam multi_norm_if_support

This modparam was introduced to enable non-p2p mode operation
on two virtual interfaces. It does not seem to be necessary to
have a separate module parameter to do that. Instead, this option
can be enabled when any one of the interfaces is not going to be
used for p2p (ath6kl_p2p).

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>