staging: brcm80211: remove dongle firmware related debug code

When the device dies the driver could extract cpu registers on
the device to analyze the trap handling on the dongle. As the
firmware with this driver is stable this code does not belong
in the brcmfmac driver.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>