mfd: tps68470: Drop unused MODULE_DEVICE_TABLE

The Kconfig currently controlling compilation of this code is:

drivers/mfd/Kconfig:config MFD_TPS68470
drivers/mfd/Kconfig:    bool "TI TPS68470 Power Management / LED chips"

...meaning that it currently is not being built as a module by anyone.

Hence we remove the MODULE_DEVICE_TABLE since it is a no-op for
non-modular code.

There is no removal of <linux/module.h> here because there isn't one.
Instead, it is relying on including that implicitly from an ACPI header.

In cleaning up the ACPI instance of module.h (which also isn't strictly
needed), then this mfd driver breaks when MODULE_DEVICE_TABLE becomes
undefined here.

The easiest dependency solution is to simply defer the ACPI cleanup
until this change is present in mainline.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>