mtd: rawnand: mtk: Fix WAITRDY break condition and timeout

This fixes NAND_OP_WAITRDY_INSTR operation in the driver. Without this
change the driver waits till the system is busy, but we should wait till
the busy flag is cleared. The readl_poll_timeout() function gets a break
condition, not a wait condition.

In addition fix the timeout. The timeout_ms is given in ms, but the
readl_poll_timeout() function takes the timeout in us. Multiple the
given timeout by 1000 to convert it.

Without this change, the driver does not work at all, it doesn't even
identify the NAND chip.

Fixes: 5197360f

 ("mtd: rawnand: mtk: Convert the driver to exec_op()")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210309000107.1368404-1-hauke@hauke-m.de