iomap: treat inline data in iomap_writepage_map as an I/O error

iomap_writepage_map aready warns about inline data, but then just ignores
it.  Treat it as an error and return -EIO.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231207072710.176093-3-hch@lst.de


Signed-off-by: Christian Brauner <brauner@kernel.org>