brcmfmac: remove unused defintion

The define EBRCMF_UNSUPPORTED is not used in the source file so this
patch removes it.
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Daniel (Deognyoun) Kim <dekim@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>

drivers/net/wireless/brcm80211/brcmfmac/feature.c

@@ -23,11 +23,6 @@
 #include "fwil.h"
 #include "feature.h"
 
-/*
- * firmware error code received if iovar is unsupported.
- */
-#define EBRCMF_FEAT_UNSUPPORTED		23
-
 /*
  * expand feature list to array of feature strings.
  */