Fix diskstats stats using sysfs (#394)
Fix diskstats stats using sysfs (#394)

/sys/block/<dev> is normally a symlink while code previously checked
for a directory.

Added flush request and time spend flushing diskstats for kernel 5.5+
to sysfs.

Signed-off-by: Luiz Angelo Daros de Luca <e0ce3b3937784afcb22dfe444e84ca044934412f@gmail.com>
prometheus/procfs,prometheus/procfs