powerpc/configs/6xx: Drop no longer needed CONFIG_TIMER_STATS

Since commit dfb4357d ("time: Remove CONFIG_TIMER_STATS") we no
longer need to set CONFIG_TIMER_STATS in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/ppc6xx_defconfig

@@ -1144,7 +1144,6 @@ CONFIG_DEBUG_VM=y
 CONFIG_DEBUG_HIGHMEM=y
 CONFIG_DEBUG_STACKOVERFLOW=y
 CONFIG_DEBUG_SHIRQ=y
-CONFIG_TIMER_STATS=y
 CONFIG_DEBUG_RT_MUTEXES=y
 CONFIG_DEBUG_SPINLOCK=y
 CONFIG_DEBUG_MUTEXES=y