ACPI / PMIC: remove modular references from non-modular code

The Kconfig currently controlling compilation of these files are:

drivers/acpi/Kconfig:menuconfig PMIC_OPREGION
drivers/acpi/Kconfig:   bool "PMIC (Power Management Integrated Circuit) operation region support"

drivers/acpi/Kconfig:config BXT_WC_PMIC_OPREGION
drivers/acpi/Kconfig:   bool "ACPI operation region support for BXT WhiskeyCove PMIC"

drivers/acpi/Kconfig:config XPOWER_PMIC_OPREGION
drivers/acpi/Kconfig:   bool "ACPI operation region support for XPower AXP288 PMIC"

...meaning they currently are not being built as a module by anyone.

Lets remove the couple traces of modular infrastructure use, so that
when reading the code there is no doubt it is builtin-only.

We delete the MODULE_LICENSE tag etc. since all that information
is already contained at the top of the file in the comments.

One file was using module_init.  Since module_init translates to
device_initcall in the non-modular case, the init ordering remains
unchanged with this commit.

In one case we replace the module.h with export.h since that file
is exporting some symbols, but does not use __init.  The other two
are using __init and so module.h gets replaced with init.h there.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>