Required for Apple and Microsoft -compatible HID-over-SPI drivers.
Most logic was already implemented in commit 3c0867343819
"spibus: extend API: add cs_delay ivar, KEEP_CS and NO_SLEEP flags".
It dissallowed driver sleeps in the interrupt context. This commit
extends this feature on ddb/kdb context and adds some new properties:
- Skip driver locking if SPI functions were called from kdb/ddb.
- Reinitialize controller if kdb/ddb initiated SPI transfer has interrupted another already running one. Does not work very reliable yet.