of: use pr_fmt prefix for all console printing
Clean-up all the DT printk functions to use common pr_fmt prefix.
Some print statements such as kmalloc errors were redundant, so just
drop those.
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>