net: davinci: emac: Convert to devm_* api

Use devm_ioremap_resource instead of devm_request_mem_region()/devm_ioremap()
and devm_request_irq() instead of request_irq().

This ensures more consistent error values and simplifies error paths.

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>