spi: Fixes for v4.6

A couple of driver specific fixes here that came in since the merge
window plus one core fix for locking in cases where a client driver
grabs a lock on the whole bus for an extended series of operations that
was introduced by the changes to support accelerated flash operations.
Merge remote-tracking branches 'spi/fix/omap2' and 'spi/fix/rockchip' into spi-linus