dmaengine: imx-sdma: fix init of uart scripts

Commit b98ce2f4e32b ("dmaengine: imx-sdma: add uart rom script") broke
uart rx on imx5 when using sdma firmware from older Freescale 2.6.35
kernel. In this case reading addr->uartXX_2_mcu_addr was going out of
bounds of the firmware memory and corrupting the uart script addresses.

Simply adding a bounds check before accessing addr->uartXX_2_mcu_addr
does not work as the uartXX_2_mcu_addr members are now beyond the size
of the older firmware and the uart addresses would never be populated
in that case. There are other ways to fix this but overall the logic
seems clearer to me to revert the uartXX_2_mcu_ram_addr structure
entries back to uartXX_2_mcu_addr, change the newer entries to
uartXX_2_mcu_rom_addr and update the logic accordingly.

I have tested this patch on:
1. An i.MX53 system with sdma firmware from Freescale 2.6.35 kernel.
   Without this patch uart rx is broken in this scenario, with the
   patch uart rx is restored.
2. An i.MX6D system with no external sdma firmware. uart is okay with
   or without this patch.
3. An i.MX8MM system using current sdma-imx7d.bin firmware from
   linux-firmware. uart is okay with or without this patch and I
   confirmed the rom version of the uart script is being used which was
   the intention and reason for commit b98ce2f4e32b ("dmaengine:
   imx-sdma: add uart rom script") in the first place.

Fixes: b98ce2f4e32b ("dmaengine: imx-sdma: add uart rom script")
Cc: stable@vger.kernel.org
Signed-off-by: Kevin Groeneveld <kgroeneveld@lenbrook.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/20220410223118.15086-1-kgroeneveld@lenbrook.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

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