Change all pr_warning() calls to pr_warn(), as advised by checkpatch.pl.

Also, while modifying those pr_warning() calls change hardcoded
function names to use '"%s:", __func__' instead, and converted acronym
usage to upper case.
Signed-off-by: NRobert Tivy <rtivy@ti.com>
Signed-off-by: NSekhar Nori <nsekhar@ti.com>