perf/arm_pmu_platform: Clean up with dev_printk

Nearly all of the messages we can log from the platform device code
relate to the specific PMU device and the properties we're parsing from
its DT node. In some cases we use %pOF to point at where something was
wrong, but even that is inconsistent. Let's convert these logs to the
appropriate dev_printk variants, so that every issue specific to the
device and/or its DT description is clearly and instantly attributable,
particularly if there is more than one PMU node present in the DT.

The local refactoring in a couple of functions invites some extra
cleanup in the process - the init_fn matching can be streamlined, and
the PMU registration failure message moved to the appropriate place and
log level.

CC: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/10a4aacdf071d0c03d061c408a5899e5b32cc0a6.1616774562.git.robin.murphy@arm.com


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