i2c: uniphier: issue STOP only for last message or I2C_M_STOP

i2c: uniphier: issue STOP only for last message or I2C_M_STOP

This driver currently emits a STOP if the next message is not
I2C_MD_RD.  It should not do it because it disturbs the I2C_RDWR
ioctl, where read/write transactions are combined without STOP
between.

Issue STOP only when the message is the last one _or_ flagged with
I2C_M_STOP.

Fixes: dd6fd4a32793 ("i2c: uniphier: add UniPhier FIFO-less I2C driver")
Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>