ARM: imx_v6_v7_defconfig: Select CONFIG_PROVE_LOCKING

This is very useful for detecting 'circular locking dependency' issues.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/configs/imx_v6_v7_defconfig

@@ -270,6 +270,7 @@ CONFIG_NLS_ISO8859_15=m
 CONFIG_NLS_UTF8=y
 CONFIG_MAGIC_SYSRQ=y
 # CONFIG_SCHED_DEBUG is not set
+CONFIG_PROVE_LOCKING=y
 # CONFIG_DEBUG_BUGVERBOSE is not set
 # CONFIG_FTRACE is not set
 # CONFIG_ARM_UNWIND is not set