brcmfmac: use one list of event defintions

Currently, adding a new event requires modification in two source
files. Use macro definition to have one place and have better
maintainability.

Reviewed-by: Hante Meuleman <meuleman@broadcom.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>