read_current_timer() cleanups

- All implementations can be __devinit

- The function prototypes were in asm/timex.h but they all must be the same,
  so create a single declaration in linux/timex.h.

- uninline the sparc64 version to match the other architectures

- Don't bother #defining ARCH_HAS_READ_CURRENT_TIMER to a particular value.

[ezk@cs.sunysb.edu: fix build]
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/sparc64/kernel/time.c b/arch/sparc64/kernel/time.c
index 4352ee4..d204f1a 100644
--- a/arch/sparc64/kernel/time.c
+++ b/arch/sparc64/kernel/time.c
@@ -1707,6 +1707,11 @@
 	misc_deregister(&rtc_mini_dev);
 }
 
+int __devinit read_current_timer(unsigned long *timer_val)
+{
+	*timer_val = tick_ops->get_tick();
+	return 0;
+}
 
 module_init(rtc_mini_init);
 module_exit(rtc_mini_exit);