brcmfmac: Remove error print for invalid key index.

brcmfmac: Remove error print for invalid key index.

When a key is set or cleared with an unsupported key index then
brcmfmac will print an error. With most wpa_supplicants this is
happening a lot. The error print is confusing and not needed.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>