Input: input_event - fix the CONFIG_SPARC64 mixup

Arnd Bergmann pointed out that CONFIG_* cannot be used in a uapi header.
Override with an equivalent conditional.

Fixes: 2e746942 ("Input: input_event - provide override for sparc64")
Fixes: 152194fe ("Input: extend usable life of event timestamps to 2106 on 32 bit systems")
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

include/uapi/linux/input.h

@@ -32,7 +32,7 @@ struct input_event {
 #define input_event_usec time.tv_usec
 #else
 	__kernel_ulong_t __sec;
-#ifdef CONFIG_SPARC64
+#if defined(__sparc__) && defined(__arch64__)
 	unsigned int __usec;
 #else
 	__kernel_ulong_t __usec;