ASoC: uniphier: remove superfluous <linux/mfd/syscon.h> inclusion

None of aio-compress.c depends on the syscon header.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Katsuhiro Suzuki <suzuki.katsuhiro@socionext.com>
Signed-off-by: Mark Brown <broonie@kernel.org>