[ARM] dma: rejig DMA initialization

Rather than having the central DMA multiplexer call the architecture
specific DMA initialization function, have each architecture DMA
initialization function use core_initcall(), and register each DMA
channel separately with the multiplexer.

This removes the array of dma structures in the central multiplexer,
replacing it with an array of pointers instead; this is more flexible
since it allows the drivers to wrap the DMA structure (eventually
allowing us to transition non-ISA DMA drivers away.)

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-shark/dma.c

@@ -13,9 +13,11 @@
 #include <asm/dma.h>
 #include <asm/mach/dma.h>
 
-void __init arch_dma_init(dma_t *dma)
+static int __init shark_dma_init(void)
 {
 #ifdef CONFIG_ISA_DMA
-	isa_init_dma(dma);
+	isa_init_dma();
 #endif
+	return 0;
 }
+core_initcall(shark_dma_init);