i2c-omap: ACK pending [R/X]DR and [R/X]RDY interrupts

ACK any pending read/write interrupts before exiting the ISR either after
completing the operation [ARDY interrupt] or in case of an error
[NACK|AL interrupt]

Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>