brcm80211: smac: remove SI_FAST() macro usage

The use of SI_FAST() macro interferes with the BCMA integration as
it causes BCMA and aiutils.c to get out of sync on what the current
core is. When everything is using BCMA we will try to add SI_FAST
functionality to BCMA to avoid unnecessary core switching.

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