spi: spi_s3c24xx driver must init completion

spi: spi_s3c24xx driver must init completion

The s3c24xx_spi_txrx() function should initialise the completion each time
before using it, otherwise we end up with the possibility of returning success
before the interrupt handler has processed all the data.

Signed-off-by: Ben Dooks <ben-linux@fluff.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>