pxa2xx_spi: prevent panic case setup() fails

setup() may fail before ctldata is set, causing a kernel panic on
cleanup().

Signed-off-by: Daniel Ribeiro <drwyrm@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>