clock-imx35: fix divider if ahb is source for ipg_per

According to the Datasheet:
"i.MX35 (MCIMX35) Multimedia Applications Processor Reference Manual,
Rev. 2" "Table 14-6. PDR0 Field Descriptions" the divider is
CCM_PER_AHB[3:0] + 1.

This patch adds the missing + 1.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx3/clock-imx35.c

@@ -292,7 +292,7 @@ static unsigned long get_rate_ipg_per(struct clk *clk)
 		return get_rate_arm() / (div + 1);
 	} else {
 		div = (pdr0 >> 12) & 0x7;
-		return get_rate_ahb(NULL) / div;
+		return get_rate_ahb(NULL) / (div + 1);
 	}
 }