board: stmark2: add i2c0 pinmux pad configuration

Add CFG option to enable proper pinmux pad setting for i2c0.

Signed-off-by: Angelo Dureghello <angelo@kernel-space.org>
diff --git a/include/configs/stmark2.h b/include/configs/stmark2.h
index 05de376..6edaf73 100644
--- a/include/configs/stmark2.h
+++ b/include/configs/stmark2.h
@@ -97,4 +97,6 @@
 
 #define CFG_MCFTMR
 
+#define CFG_SYS_I2C_0
+
 #endif /* __STMARK2_CONFIG_H */