sched: Update rq->cpu_capacity_orig on thermal (LMH) throttling

capacity_orig_of is supposed to return the maximum capacity
of the a CPU based on its FMAX. Given that LMH may limit
the FMAX, let's make sure that cpu_capacity_orig is also
updated when that happens.

Change-Id: I82fbd8587d7b4b82b50fb80d6c9dc78344837bf5
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>