dmaengine: imx-sdma: Support allocate memory from internal SRAM (iram)

Allocate memory from SoC internal SRAM to reduce DDR access and keep DDR in
lower power state (such as self-referesh) longer.

Check iram_pool before sdma_init() so that ccb/context could be allocated
from iram because DDR maybe in self-referesh in lower power audio case
while sdma still running.

Reviewed-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Signed-off-by: Nicolin Chen <b42378@freescale.com>
Signed-off-by: Joy Zou <joy.zou@nxp.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20240329-sdma_upstream-v4-1-daeb3067dea7@nxp.com


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