mmc: meson-gx: do not use memcpy_to/fromio for dram-access-quirk

mmc: meson-gx: do not use memcpy_to/fromio for dram-access-quirk

The memory at the end of the controller only accepts 32bit read/write
accesses, but the arm64 memcpy_to/fromio implementation only uses 64bit
(which will be split into two 32bit access) and 8bit leading to incomplete
copies to/from this memory when the buffer is not multiple of 8bytes.

Add a local copy using writel/readl accesses to make sure we use the right
memory access width.

The switch to memcpy_to/fromio was done because of 285133040e6c
("arm64: Import latest memcpy()/memmove() implementation"), but using memcpy
worked before since it mainly used 32bit memory acceses.

Fixes: 103a5348c22c ("mmc: meson-gx: use memcpy_to/fromio for dram-access-quirk")
Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Suggested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210928073652.434690-1-narmstrong@baylibre.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>