perf/arm_pmu_platform: Use dev_err_probe() for IRQ errors

By virtue of using platform_irq_get_optional() under the covers,
platform_irq_count() needs the target interrupt controller to be
available and may return -EPROBE_DEFER if it isn't. Let's use
dev_err_probe() to avoid a spurious error log (and help debug any
deferral issues) in that case.

Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/073d5e0d3ed1f040592cb47ca6fe3759f40cc7d1.1616774562.git.robin.murphy@arm.com


Signed-off-by: Will Deacon <will@kernel.org>