dt-bindings: memory: ti-emif: add edac support under emif

Certain revisions of the TI EMIF IP contain ECC support in them. Reflect
this in the DT binding. Also, add interrupts property as a required
property for the emif controller, as all revisions of the emif IP contain
interrupt support; this might remain unused by the kernel driver though.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>