ACPICA: Clean up redudant definitions already defined elsewhere

Since mis-order issues have been solved, we can cleanup redundant
definitions that already have defaults in <acpi/platform/acenv.h>.

This patch removes redudant environments for __KERNEL__ surrounded code.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>