Staging: udlfb: Add functions to expose sysfs metrics and controls

Staging: udlfb: Add functions to expose sysfs metrics and controls

Add sysfs controls for edid and performance metrics

There are 8 new files exposed in /sys/class/graphics/fb*

edid - returns 128 byte edid blog, suitable for parsing with parse-edid
metrics_bytes_identical
metrics_bytes_rendered
metrics_bytes_sent
metrics_cpu_kcycles_used
metrics_misc
and metrics_reset, which resets all perf metrics to zero

The 6 perf metrics are of type atomic_t.
So these metrics return precise results for short benchmarks, but
any test approx a minute or longer runtime may roll over.

Signed-off-by: Bernie Thompson <bernie@plugable.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>