omap3: beagle: Fix build warning

This patch fixes the warning dure to recent changes to the board
configuration:
cmd_i2c.o cmd_i2c.c -c
cmd_i2c.c:109:1: warning: missing braces around initializer
cmd_i2c.c:109:1: warning: (near initialization for 'i2c_no_probes[0]')

Signed-off-by: Sanjeev Premi <premi@ti.com>
Cc: Jason Kridner <jkridner@beagleboard.org>
Acked-by: Jason Kridner <jdk@ti.com>

include/configs/omap3_beagle.h

@@ -118,7 +118,7 @@
 #define CONFIG_I2C_MULTI_BUS		1
 
 /* Probe all devices */
-#define CONFIG_SYS_I2C_NOPROBES		{0x0, 0x0}
+#define CONFIG_SYS_I2C_NOPROBES		{{0x0, 0x0}}
 
 /* USB */
 #define CONFIG_MUSB_UDC			1