ACPICA: Remove unused ACPI_FREE_BUFFER macro. No functional change.

This macro is no longer used by ACPICA and it is not public.
Also update comments related to the use of ACPI_ALLOCATE_BUFFER and
the use of acpi_os_free (kfree is equivalent and prefered in the
kernel) to free the buffer.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/acpica/utalloc.c b/drivers/acpi/acpica/utalloc.c
index 814267f..1851762 100644
--- a/drivers/acpi/acpica/utalloc.c
+++ b/drivers/acpi/acpica/utalloc.c
@@ -302,9 +302,13 @@
 		return (AE_BUFFER_OVERFLOW);
 
 	case ACPI_ALLOCATE_BUFFER:
-
-		/* Allocate a new buffer */
-
+		/*
+		 * Allocate a new buffer. We directectly call acpi_os_allocate here to
+		 * purposefully bypass the (optionally enabled) internal allocation
+		 * tracking mechanism since we only want to track internal
+		 * allocations. Note: The caller should use acpi_os_free to free this
+		 * buffer created via ACPI_ALLOCATE_BUFFER.
+		 */
 		buffer->pointer = acpi_os_allocate(required_length);
 		break;