kernel: cleanup use of naked unsigned in _new_thread

There are a few places that we used an naked unsigned type, lets be
explicit and make it 'unsigned int'.

Change-Id: I33fcbdec4a6a1c0b1a2defb9a5844d282d02d80e
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
6 files changed