ACPICA: acpiexec: Do not put STDIN into raw mode unless it is a terminal.

Eliminate an error message for batch-mode processing on unix
systems. ACPICA BZ 1114.

This patch is mainly for fixing the issues of acpiexec which is not in the
Linux upstream.

Link: https://bugs.acpica.org/show_bug.cgi?id=1114


Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>