ACPI: EC: Fix debugfs_create_*() usage

acpi_ec.gpe is "unsigned long", hence treating it as "u32" would expose
the wrong half on big-endian 64-bit systems.  Fix this by changing its
type to "u32" and removing the cast, as all other code already uses u32
or sometimes even only u8.

Fixes: 1195a098 (ACPI: Provide /sys/kernel/debug/ec/...)
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>