staging: brcm80211: assigned physical addresses in dma.c correct type

Code cleanup. Physical addresses in dma.c are all allocated by calls to
pci_alloc_consistent(). Since that call returns physical addresses as
type 'dma_addr_t', all physical addresses in dma.c were changed from
'unsigned long' to 'dma_addr_t'.

Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>