bcm2708-dmaengine: don't leak kernel address

Since commit ad67b74d ("printk: hash addresses printed with %p"),
an obfuscated kernel pointer is printed at every boot:

    bcm2835-dma fe007000.dma: DMA legacy API manager at (____ptrval____), dmachans=0x1

Remove the pointer print.

Signed-off-by: Matteo Croce <mcroce@redhat.com>