ARM: dts: omap5: Add aliases for rproc nodes

Add aliases for the DSP and IPU remoteproc processor
nodes common to all OMAP5 boards. The aliases uses
the stem "rproc", and are identical to the values
chosen on OMAP4 boards.

The aliases can be overridden, if needed, in the
respective board files.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>