Add missing kernel config symbol probably some dependency uncovered by
my local perf related and enabled kernel config options.
ARM PMU framework (ARM_PMU) [Y/n/?] y
Freescale i.MX8 DDR perf monitor (FSL_IMX8_DDR_PMU) [N/m/y/?] (NEW)
Signed-off-by: Petr Štetiar <ynezz@true.cz>