brcmsmac: update transmit gain table for lcn phy

Update the transmit gain table for bcm4313 chip family.

Tested-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>