Driver core: convert SPI code to use struct device

Converts from using struct "class_device" to "struct device" making
everything show up properly in /sys/devices/ with symlinks from the
/sys/class directory.

Cc: <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --cc drivers/spi/pxa2xx_spi.c
Simple merge

diff --cc drivers/spi/spi.c
Simple merge

diff --cc drivers/spi/spi_bitbang.c
Simple merge

diff --cc drivers/spi/spi_butterfly.c
Simple merge

diff --cc include/linux/spi/spi.h
Simple merge