ARM: OMAP: Remove unused pieces of legacy DMA API

We're moving to the dmaengine API, so let's remove the unused
pieces of the omap legacy DMA code to make sure we don't get
any new users for these:

omap_set_dma_color_mode
omap_set_dma_src_index
omap_set_dma_dest_index
omap_dma_unlink_lch
omap_clear_dma
omap_dma_running
omap_dma_set_prio_lch
omap_set_dma_dst_endian_type
omap_set_dma_src_endian_type
omap_get_dma_index
omap_dma_disable_irq
omap_request_dma_chain
omap_free_dma_chain
omap_dma_chain_a_transfer
omap_start_dma_chain_transfers
omap_stop_dma_chain_transfers
omap_get_dma_chain_index
omap_get_dma_chain_dst_pos
omap_get_dma_chain_src_pos
omap_modify_dma_chain_params
omap_dma_chain_status

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>