mmc: sunxi: fix mojibake in module metadata

It had an U+FFFD: not a corrupted character but a literal well-formed
replacement marker.

Signed-off-by: Adam Borowski <kilobyte@angband.pl>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>