board: ti: DRA7: Add DP83867 TI phy for rev c

Enable the TI DP83867 Giga bit phy on the
dra7 rev c board.  The rx and tx internal
delays are need for this board so the usage
of RGMII_ID is required.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Acked-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>