ACPICA: Use uintptr_t and offsetof() in Linux kernel builds

ACPICA: Use uintptr_t and offsetof() in Linux kernel builds

To avoid "performing pointer subtraction with a null pointer has
undefined behavior" compiler warnings, use uintptr_t and offsetof()
that are always available during Linux kernel builds to define
acpi_uintptr_t and the ACPI_TO_INTEGER() and ACPI_OFFSET() macros.

Based on earlier proposal from Arnd Bergmann.

Link: https://lore.kernel.org/linux-acpi/20210927121338.938994-1-arnd@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>