I2C: Fix OMAP I2C status register handling in IRQ processing

The IRQ handler in omap-i2c.c can sometimes clear status bits without
actually processing them.  In particular, error status bits will be
ignored if any of the ARDY, RRDY, RDR, XRDY, or XDR bits are
concurrently set.

Signed-off-by: Seth Forshee <seth.forshee@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>