board/olpc/xo-1: enable ACPI

The DCON drivers depends on it.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/olpc/xo-1/linux.config

@@ -6,7 +6,7 @@ CONFIG_HZ_100=y
 CONFIG_KEXEC=y
 CONFIG_PHYSICAL_START=0x400000
 CONFIG_CMDLINE_BOOL=y
-# CONFIG_ACPI is not set
+CONFIG_ACPI=y
 CONFIG_CPU_IDLE=y
 CONFIG_CPU_IDLE_GOV_LADDER=y
 CONFIG_OLPC=y