ACPICA: ASL-ASL+ converter: make root file a parameter for cv_init_file_tree

ACPICA commit 5d160cc86cca440eac7055f981e48bc14d4eb9f7

This decouples cv_init_file_tree from acpi_gbl_output_file and allows
it to be called independently of acpi_os_redirect_output()

Link: https://github.com/acpica/acpica/commit/5d160cc8


Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>