AM3517 EVM: Enable I2C support

There are multiple devices connected to I2C bus on AM3517EVM
(for instance audio codec, IO expander etc). Enable I2C support
in the default kernel configuration for AM3517 EVM.

Signed-off-by: Sriramakrishnan <srk@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>