misc/pvpanic : break dependency on ACPI

The pvpanic driver is available for architectures that do not
support ACPI.So break the dependency.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>