platform/x86: msi-ec: Ensure dmi_system_id is defined

platform/x86: msi-ec: Ensure dmi_system_id is defined

Currently <linux/acpi.h> includes <linux/mod_devicetable.h> and thus
dmi_system_id is available for the driver. To disentangle includes
<linux/acpi.h> will be changed to only include the header for
acpi_device_id instead of the full <linux/mod_devicetable.h>. To prepare
for that include the dedicated header for struct dmi_device_id.

Acked-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://patch.msgid.link/600c7ab3263dcb8cee39b43dbd313eba8abef376.1782808461.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>