Revert "kernel: Convert formatter strings to use PRI defines"

This reverts commit 7b9dc107.

We revert this as we intent to move away from {u}int{8,16,32,64}_t types
to our own internal types for sized variables so we shouldn't need the
PRI macros anymore.

Change-Id: I1d9d797fee47ca266867ae65656c150f8fe2adb2
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>