sun4m: move DMA device wiring from sparc32_dma_init() to sun4m_hw_init()

sun4m: move DMA device wiring from sparc32_dma_init() to sun4m_hw_init()

By using the sysbus interface it is possible to wire up the esp/le devices
to the sun4m DMA controller directly during sun4m_hw_init() instead of
passing qemu_irqs into the sparc32_dma_init() function.

This is an intermediate step to allow further reorganisation as more logic
is moved into the relevant SPARC32 DMA devices; there will be a final
refactoring of sparc32_dma_init() once this work is complete.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Artyom Tarasenko <atar4qemu@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>