enable errata 430973 workaround

As mentioned at [1] u-boot unconditionally enabled a workaround
for errata 430973. Although this no longer applies for sillicon
revision r1p7 like the ccgx, it causes segfaults when enabled
in the the bootloader. Since deploying a new MLO is not that easy
turn on the workaround in linux. The code at [2] can trigger
this condition.

[1] http://lists.denx.de/pipermail/u-boot/2013-July/158377.html
[2] github.com/downloads/ssvb/ssvb.github.com/ssvb-cpuburn-a8.S

arch/arm/configs/am3517_ccgx_defconfig

@@ -368,7 +368,7 @@ CONFIG_ARM_L1_CACHE_SHIFT=6
 CONFIG_ARM_DMA_MEM_BUFFERABLE=y
 CONFIG_ARM_NR_BANKS=8
 CONFIG_MULTI_IRQ_HANDLER=y
-# CONFIG_ARM_ERRATA_430973 is not set
+CONFIG_ARM_ERRATA_430973=y
 # CONFIG_ARM_ERRATA_458693 is not set
 # CONFIG_ARM_ERRATA_460075 is not set
 # CONFIG_ARM_ERRATA_720789 is not set