CHIPS: Fix potential starvation in cfi_cmdset_0001

The patch below fixes a potential starvation issue that can arise when
there is contention on a chip during a period when a process is
currently writing to it.  The starvation is avoided by conditionally
rescheduling when the chip is left in a state usable by other processes.

Signed-off-by: Josh Boyer <jdub@us.ibm.com>
Signed-off-by: Tom Gall <tom_gall@vnet.ibm.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>