clocksource: Change __ARCH_HAS_CLOCKSOURCE_DATA to a CONFIG option

The machinery for __ARCH_HAS_CLOCKSOURCE_DATA assumed a file in
asm-generic would be the default for architectures without their own
file in asm/, but that is not how it works.

Replace it with a Kconfig option instead.

Link: http://lkml.kernel.org/r/4E288AA6.7090804@zytor.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 38280ef..0a9820a 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -101,6 +101,9 @@
 	bool
 	default y
 
+config ARCH_CLOCKSOURCE_DATA
+	def_bool y
+
 config SCHED_OMIT_FRAME_POINTER
 	bool
 	default y