mmc: atmel-mci: Fix debugfs on 64-bit platforms

"atmel_mci.pending_events" and "atmel_mci.completed_events" are
"unsigned long", i.e. 32-bit or 64-bit, depending on the platform.
Hence casting their addresses to "u32 *", and calling
debugfs_create_x32() breaks operation on 64-bit platforms.

Fix this by using the new debugfs_create_xul() helper instead.

Fixes: deec9ae3

 ("atmel-mci: debugfs support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20191025094130.26033-5-geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>