mtd: nand: sunxi: Fix the non-polling case in sunxi_nfc_wait_events()

[ Upstream commit 19649e2c16fbc94b664f7074ec4fa9f15292fdce ]

wait_for_completion_timeout() returns 0 if a timeout occurred, 1
otherwise. Fix the sunxi_nfc_wait_events() accordingly.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>