powerpc/mpc85xx: Fix the I2C bus speed error on p1022

The source clock frequency of I2C bus on p1022 is the platform(CCB)
clock, not CCB/2. The wrong source clock frequency leads to wrong
I2C bus speed setting. so, fixed it.

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>

arch/powerpc/cpu/mpc85xx/speed.c

@@ -399,7 +399,8 @@ int get_clocks (void)
 	 * AN2919.
 	 */
 #if defined(CONFIG_MPC8540) || defined(CONFIG_MPC8541) || \
-	defined(CONFIG_MPC8560) || defined(CONFIG_MPC8555)
+	defined(CONFIG_MPC8560) || defined(CONFIG_MPC8555) || \
+	defined(CONFIG_P1022)
 	gd->arch.i2c1_clk = sys_info.freq_systembus;
 #elif defined(CONFIG_MPC8544)
 	/*