[PATCH] SPI: infrastructure to initialize spi_device.mode early

This patch adds earlier initialization of spi_device.mode, as needed
on boards using nondefault chipselect polarity.  An example would be
ones using the RS5C348 RTC without an external signal inverter between
the RTC chipselect and the SPI controller.

Without this mechanism, the first setup() call for that chip would
wrongly enable chips, corrupting transfers to/from other chips sharing
that SPI bus.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>