spi: Add a timeout when waiting for transfers

Don't wait indefinitely for transfers to complete but time out after 10ms
more than we expect the transfer to take on the wire.

Signed-off-by: Mark Brown <broonie@linaro.org>
(cherry picked from commit 16a0ce4e)
(cherry picked from commit 21113987c8a44c4ece385c368cd7e9058311da10)