Current implementation of omap_i2c_isr doesn't work on OMAP5910 (Too
much work in one IRQ). Interrupt service routine is broken in these
aspects:
* it tries to ack interrupt by writing to read-only status register.
* it doesn't ackowledge interrupt properly by reading interrupt vector
  register.
I'm assuming that driver works correctly on other OMAPs (right? ;-)), so
proposed patch adds interrupt service routine for 15xx cpus and deletes
rev1 stuff from omap_i2c_isr. Tested on OMAP5910 with DS1339 clock on
I2C bus.
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>