soc: qcom: add scm-errata driver

This driver exposes a debugfs interface intended for advanced
system debugging/profiling usecases where it may be desirable
to enable or disable certain hardware errata workarounds at
runtime, via an scm call.

Presently, a single debugfs node is implemented:
  /sys/kernel/debug/scm_errata/kryo_e74_e75
This allows Kryo errata 74 and 75 workarounds to be toggled
off or on (on affected devices) by echoing 0 or 1 to the file.

Change-Id: I6edf39757416130a7b716dcdab1a601f27dfac5a
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>