Recent changes to the DMA code has resulting in the IMX driver failing
I2C transfers when the buffer has been vmalloc. Only perform DMA
transfers if the message has the I2C_M_DMA_SAFE flag set, indicating
the client is providing a buffer which is DMA safe.

This is a minimal fix for stable. The I2C core provides helpers to
allocate a bounce buffer. For a fuller fix the master should make use
of these helpers.

Fixes: 4544b9f2 ("dma-mapping: Add vmap checks to dma_map_single()")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>