This adds a backend for flashdev that simulates a flash device with
adjustable delays to simulate real flash devices and offers
configurable flash parameters. This also migrates the JFFS2
filesystem tests to the flashdev framework and eliminates the
purpose-built simulated flash in the testsuite in favor of a more
generic and widely usable solution.
This adds generic JFFS2 interworking code that allows JFFS2 to be used
on top of any flashdev backend. It currently only supports NOR flashdev
backends.
