staging: brcm80211: remove include file d11ucode_ext.h

Include file required by wl_ucode.h only so merged content of
d11ucode_ext.h into that include file to reduce number of include
files in the driver.

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