brcm80211: smac: remove phy api bypass in rate.h

Obviously the phy api should be used to interface with the phy. In
rate.h a table within phy was accessed directly by declaring the
table extern in rate.h itself. This patch fixes this using the
provided api function to obtain the table reference. This bypass
was found by a sparse warning on the table not being defined static.

Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>