i2c-davinci: Remove useless IVR read

Interrupts are enabled at the point where the DAVINCI_I2C_IVR_REG is read,
so unless an interrupt happened just at that moment, no interrupt would be
pending. Even though documentation implies you should do this, I see no
reason. If slave support is added, this read would cause a hard to
reproduce bug.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>