mpc512x: Fix problem with I2C access before relocation

This is needed for the upcoming esd MECP5123 board port which uses
I2C EEPROM for environment storage.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
Acked-by: Heiko Schocher<hs@denx.de>
diff --git a/cpu/mpc512x/i2c.c b/cpu/mpc512x/i2c.c
index 97bda0d..e2d9097 100644
--- a/cpu/mpc512x/i2c.c
+++ b/cpu/mpc512x/i2c.c
@@ -33,7 +33,7 @@
 #include <i2c.h>
 
 /* by default set I2C bus 0 active */
-static unsigned int bus_num = 0;
+static unsigned int bus_num __attribute__ ((section (".data"))) = 0;
 
 #define I2C_TIMEOUT	100
 #define I2C_RETRIES	3