Wait for WIP to clear before returning from erase operations too.

Wrong-block-type race condition errors went away after adding the WIP
check after flash write operations, then came back once (isolated
incident) while running a series of tests which had written enough
flash blocks that ks_flash may have finally had to erase something
rather than just zeroing.

Code inspection confirmed that the erase code was not waiting for WIP
to clear before exiting.  Difficult to prove that this was the cause
of an unreproducible failure, but seems like a likely candidate given
previous behavior and change should be harmless, so adding it.

Timeout for this flag check is 2000 ms, which is what other
erase-related WIP flag checks were already using.

0 files changed, 0 insertions, 0 deletions