Add ksdk spi shim driver

[zephyrbot]

Reported by Maureen Helm:

Create a shim driver based on ext/hal/ksdk/drivers/fsl_dspi.*

(Imported from Jira ZEP-1374)

[zephyrbot]

by Mark Linkmeyer:

Fixing incorrect priority

[zephyrbot]

Blocks GH-2942