When an XRDY/XDR is hit, wait for XUDF before writing data to DATA_REG.
Otherwise some data bytes can be lost while transferring them from the
memory to the I2C interface.

Do a Busy-wait for XUDF, before writing data to DATA_REG. While waiting
if there is NACK | AL, set the appropriate error flags, ack the pending
interrupts and return from the ISR.
Signed-off-by: NMoiz Sonasath <m-sonasath@ti.com>
Signed-off-by: NVikram pandita <vikram.pandita@ti.com>
[ben-linux@fluff.org: fixed mail format and added i2c-omap to subject]
Signed-off-by: NBen Dooks <ben-linux@fluff.org>