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>

arch/ia64/Kconfig

@@ -101,6 +101,9 @@ config GENERIC_IOMAP
 	bool
 	default y
 
+config ARCH_CLOCKSOURCE_DATA
+	def_bool y
+
 config SCHED_OMIT_FRAME_POINTER
 	bool
 	default y

arch/ia64/include/asm/clocksource.h

@@ -3,8 +3,6 @@
 #ifndef _ASM_IA64_CLOCKSOURCE_H
 #define _ASM_IA64_CLOCKSOURCE_H
 
-#define __ARCH_HAS_CLOCKSOURCE_DATA
-
 struct arch_clocksource_data {
 	void *fsys_mmio;        /* used by fsyscall asm code */
 };