net: phy: ti: Allow the driver to be more configurable

Not all devices use the same internal delay or fifo depth.
Add the ability to set the internal delay for rx or tx and the
fifo depth via the devicetree.  If the value is not set in the
devicetree then set the delay to the default.

If devicetree is not used then use the default defines within the
driver.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Tested-by: Mugunthan V N <mugunthanvnm@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>