qtnfmac: pass sgi rate info flag to wireless core

SGI should be passed to wireless core as a part of rate structure.
Otherwise wireless core performs incorrect rate calculation when
SGI is enabled in hardware but not reported to host.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>