dmaengine: Remove device_prep_dma_imm_data from struct dma_device

The device_prep_dma_imm_data() method isn't implemented or invoked by
any code since commit 80ade22c ("misc: mic: remove the MIC drivers").

Remove it, shrinking struct dma_device by a few bytes.

Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
Link: https://lore.kernel.org/r/20250210-dmaengine-drop-imm-data-v1-1-e017766da2fa@amd.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>