acpi: add module.h to files implicitly using/relying on it.

These files are using standard module API things like MODULE_AUTHOR
etc. and so should not be relying on an implicit presence of the
module.h header.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/acpi/ec_sys.c b/drivers/acpi/ec_sys.c
index 22f918b..6c47ae9 100644
--- a/drivers/acpi/ec_sys.c
+++ b/drivers/acpi/ec_sys.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/acpi.h>
 #include <linux/debugfs.h>
+#include <linux/module.h>
 #include "internal.h"
 
 MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");