staging: brcm80211: removed set_fs/get_fs/get_ds calls from brcmf_dev_ioctl()

brcmf_dev_ioctl() does not provide a user space buffer to
brcmf_netdev_ioctl_priv. Hence these calls are not necessary.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>