mmc: dw_mmc: Fix debugfs on 64-bit platforms

"dw_mci.pending_events" and "dw_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: f95f3850

 ("mmc: dw_mmc: Add Synopsys DesignWare mmc host driver.")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20191025094130.26033-7-geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>