ARM: AM33XX: clock: Add dcan clock aliases for device-tree

ARM: AM33XX: clock: Add dcan clock aliases for device-tree

Currently, the device names for the dcan module follows the
format "dcan.X", where 'X' is the dcan instance number.
On other side, driver may request for clock with/without con_id
and dev_id, and it is expected that platform should respect this
request and return the requested clock handle.

Now, when using device tree, the format of the device name created
by OF layer is different, "<reg-address>.<device-name>",
assuming that the device-tree "reg" property is specified.
This causes the look-up failure for clock node in dcan driver

To fix this add new dcan clock alias for using device-tree.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <robherring2@gmail.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>