ARM: OMAP2: Delete an unnecessary check

The of_node_put() function tests whether its argument is NULL and then
returns immediately if so.  Furthermore, the kerneldoc for
of_node_put() explicitly supports passing in a NULL pointer as its
argument.  Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
[paul@pwsan.com: dropped the omap_device.c and omap_hwmod.c changes for
 now, edited the commit message accordingly and to note the documented
 "contract"]
Reviewed-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>