mmc: atmel-mci: Remove superfluous cast in debugfs_create_u32() call

"atmel_mci.state" is an enum, which is compatible with u32, so there is
no need to cast its address, preventing further compiler checks.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20191025094130.26033-6-geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>