mmc: xenon: Add ac5 support via bounce buffer

mmc: xenon: Add ac5 support via bounce buffer

AC5/X/IM SOCs has a variant of the Xenon eMMC controller,
in which only 31-bit of addressing pass from the controller
on the AXI bus.
Since we cannot guarantee that only buffers from the first 2GB
of memory will reach the driver, the driver is configured for
SDMA mode, without 64-bit mode, overriding the DMA mask to 34-bit
to support the DDR memory mapping, which starts at offset 8GB.

Signed-off-by: Elad Nachman <enachman@marvell.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20240104173033.2836110-1-enachman@marvell.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>