X86 platform drivers: Remove EC dump from thinkpad_acpi

There is a general interface for that now (provided by
other patches in this patch series):
/sys/kernel/debug/ec/*/io

Signed-off-by: Thomas Renninger <trenn@suse.de>
CC: Alexey Starikovskiy <astarikovskiy@suse.de>
CC: Len Brown <lenb@kernel.org>
CC: linux-kernel@vger.kernel.org
CC: linux-acpi@vger.kernel.org
CC: platform-driver-x86@vger.kernel.org
CC: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
CC: ibm-acpi-devel@lists.sourceforge.net
Signed-off-by: Matthew Garrett <mjg@redhat.com>