staging: brcm80211: use d11rxhdr structure in brcms_c_recover_tsf64()

All information needed for this function is available in the d11rxhdr
structure. This is the last place where the brcms_d11rxhdr structure
so it can be removed.

Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>