spi_mpc83xx: turn off SPI unit while switching mode
Documentation clearly states, that mode should not be changed till
SPMODE_ENABLE bit set. I've seen hangs w/o this patch.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Acked-by: Kumar Gala <galak@kernel.crashing.org> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>