arch/powerpc/cpu/mpc512x/i2c.c: Fix GCC 4.6 warnings

Fix:
i2c.c: In function 'wait_for_bb':
i2c.c:81:16: warning: variable 'temp' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Anatolij Gustschin <agust@denx.de>

arch/powerpc/cpu/mpc512x/i2c.c

@@ -78,9 +78,8 @@ static int wait_for_bb (void)
 	status = mpc_reg_in (&regs->msr);
 
 	while (timeout-- && (status & I2C_BB)) {
-		volatile int temp;
 		mpc_reg_out (&regs->mcr, I2C_STA, I2C_STA);
-		temp = mpc_reg_in (&regs->mdr);
+		(void)mpc_reg_in(&regs->mdr);
 		mpc_reg_out (&regs->mcr, 0, I2C_STA);
 		mpc_reg_out (&regs->mcr, 0, 0);
 		mpc_reg_out (&regs->mcr, I2C_EN, 0);