MLK-11159-1 Revert "MLK-11114 imx: mx6qp disable double line feature"

This reverts commit 046e55efa6.

After further investigation, find the L2 cache double line fill is not the
root cause for USB or SD3.0 stress reboot failure. With the fix in USB driver,
and the L2 double line fill enabled, the reboot stress test has passed 4-days.
So revert the patch to make L2 double line fill enabled on imx6qp by default.

Signed-off-by: Robby Cai <r63905@freescale.com>

arch/arm/cpu/armv7/mx6/soc.c

@@ -1091,14 +1091,6 @@ void v7_outer_cache_enable(void)
 	if (((cache_id & L2X0_CACHE_ID_PART_MASK) == L2X0_CACHE_ID_PART_L310)
 	    && ((cache_id & L2X0_CACHE_ID_RTL_MASK) < L2X0_CACHE_ID_RTL_R3P2))
 		val &= ~(1 << 30);
-
-	/*
-	 * To i.MX6DQP, still disable double line fill feature due to system
-	 * reboot issue
-	 */
-	if (is_mx6dqp())
-		val &= ~(1 << 30);
-
 	writel(val, &pl310->pl310_prefetch_ctrl);
 
 	val = readl(&pl310->pl310_power_ctrl);