staging: brcm80211: remove mips specific include from dma.c

The include <asm/addrspace.h> has been removed as it is not
needed. None of the definitions from it are used in the source
file.

Tested on BCM63281.

Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Tested-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>