ACPI: bus: add stub acpi_dev_found() to linux/acpi.h

ACPI: bus: add stub acpi_dev_found() to linux/acpi.h

acpi_dev_found() will be used to detect if a given ACPI device is in the
system. It will be compiled in non-ACPI case, but the function is in
acpi_bus.h and acpi_bus.h can only be used in ACPI case, so this patch add
the stub function to linux/acpi.h to make compiled successfully in
non-ACPI cases.

Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Signed-off-by: Kejian Yan <yankejian@huawei.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>