spi: Zap ep93xx_spi driver and related code

Dropped becuase
- driver and related configs not used any board.
- no dm conversion.

Cc: Heiko Schocher <hs@denx.de>
Cc: Sergey Kostanbaev <sergey.kostanbaev@gmail.com>
Signed-off-by: Jagan Teki <jagan@openedev.com>
5 files changed