buses: i2c: update i2c geni driver to include irq.h

Currently, geni driver is depending on header inclusion tree for symbol
and prototypes of irq.h. If the dependent header removes the header, geni
driver is failing to compile. To fix the compilation error, include the
header(irq.h) in geni i2c driver.

Change-Id: Ic0f2d6f541a7816e293e230710ae121712510602
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>