dumpstate: Dump all block device stat

We have "UPTIME MMC PERF" but it is limited to MMC and thus has
been broken for a while in recent devices.
This CL is to add dump for all block devices stat information.

Bug: 62319771
Test: adb bugreport and check the result
Change-Id: I74e0bf0c4bf40e268dffd0abb8922f0ffb5e9692