staging: brcm80211: remove unused inline funtion from siutils.h

The header file contains a inline function, but it is not used by
the driver sources:

si_seci_init
Reviewed-by: Brett Rudley <brudley@broadcom.com>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/brcm80211/include/siutils.h

@@ -173,10 +173,6 @@ extern void si_sdio_init(si_t *sih);
 #define si_eci_init(sih) (0)
 #define si_eci_notify_bt(sih, type, val)  (0)
 #define si_seci(sih) 0
-static inline void *si_seci_init(si_t *sih, u8 use_seci)
-{
-	return NULL;
-}
 
 /* OTP status */
 extern bool si_is_otp_disabled(si_t *sih);