Removed free slot check algorithm in dw_axi_dma_set_hw_channel. For 8
DMA channels, use respective handshake slot in DMA_HS_SEL APB register.

For every channel, an dedicated slot is provided in  hardware handshake
register AXIDMA_CTRL_DMA_HS_SEL_n. Peripheral source number is
programmed in respective channel slots.
Signed-off-by: Pandith N <pandith.n@intel.com>
Tested-by: Pan Kris <kris.pan@intel.com>
Link: https://lore.kernel.org/r/20210802055454.15192-2-pandith.n@intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>