x86: clean up drivers/char/rtc.c

tons of style cleanup in drivers/char/rtc.c - no code changed:

   text    data     bss     dec     hex filename
   6400     384      32    6816    1aa0 rtc.o.before
   6400     384      32    6816    1aa0 rtc.o.after

since we seem to have a number of open breakages in this code we might
as well start with making the code more readable and maintainable.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>