ACPI: Remove one board specific WARN when ignoring timer overriding

commit 7f68b4c2e158019c2ec494b5cfbd9c83b4e5b253 upstream.

Current WARN msg is only for the ati_ixp4x0 board, while this function
is used by mulitple platforms. So this one board specific warning
is not appropriate any more.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>