wl1271: Remove calibration from join command

This patch removes the calibration performed on the first join command. The
reasoning is that this is unnecessary as devices get their calibration data
via the NVS file, and because the commands break BT coexistence.

This is actually safe, because of the implementation the calibration
was executed on the first JOIN anyway, after an ifdown/ifup the devices have
relied on the NVS for calibration anyway (== most of the time.)

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Teemu Paasikivi <ext-teemu.3.paasikivi@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>