w1: add missing Kconfig/Makefile entries for DS2431 slave driver

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
index 990f400..f1f51f1 100644
--- a/drivers/w1/slaves/Makefile
+++ b/drivers/w1/slaves/Makefile
@@ -4,6 +4,7 @@
 
 obj-$(CONFIG_W1_SLAVE_THERM)	+= w1_therm.o
 obj-$(CONFIG_W1_SLAVE_SMEM)	+= w1_smem.o
+obj-$(CONFIG_W1_SLAVE_DS2431)	+= w1_ds2431.o
 obj-$(CONFIG_W1_SLAVE_DS2433)	+= w1_ds2433.o
 obj-$(CONFIG_W1_SLAVE_DS2760)	+= w1_ds2760.o
 obj-$(CONFIG_W1_SLAVE_BQ27000)	+= w1_bq27000.o