lisa.pelt: Fixup simulate_pelt() clock on task enqueue/dequeue
lisa.pelt: Fixup simulate_pelt() clock on task enqueue/dequeue

The PELT clock is typically not available on task enqueue/dequeue,
but aligning the activations on the preceding PELT events makes the
sleep time inaccurate.

Fix that by providing a fake clock sample based on the ftrace clock
delta, rescaled using the nearest time scaling factor.

ARM-software/lisa,ARM-software/lisa,credp/lisa,credp/lisa,credp/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa