prf.c: code and style cleanup
prf.c: code and style cleanup

Some cleanups before further changes:

- Remove dead leftover from the "case 's'" code.

- Remove needless parents and casts.

- Remove "register" qualifier as it is ignored. The compiler knows
  better these days.

- Adjust tabs assuming standard 8-columns tab spacing.

- Make multi-line comments start with "/*" on a line of its own.

- Make the format string const to match  prototypes in other files.

- Declare boolean variable and parameters as bool.

Signed-off-by: Nicolas Pitre <76342682d5afc62854e1102d9578521fe1ed6813@baylibre.com>

Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr