drivers/x86: mark const init data with __initconst instead of __initdata

drivers/x86: mark const init data with __initconst instead of __initdata

As long as there is no other non-const variable marked __initdata in the
same compilation unit it doesn't hurt. If there were one however
compilation would fail with

	error: $variablename causes a section type conflict

because a section containing const variables is marked read only and so
cannot contain non-const variables.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>
Cc: platform-driver-x86@vger.kernel.org
Cc: ibm-acpi-devel@lists.sourceforge.net
Signed-off-by: Matthew Garrett <mjg@redhat.com>