x86/xen/time: Reduce Xen timer tick

Current timer tick is causing some deadline to fail.
The current high value constant was probably due to an old
bug in the Xen timer implementation causing errors if the
deadline was in the future.

This was fixed in Xen commit:
19c6cbd90965 xen/vcpu: ignore VCPU_SSHOTTMR_future

Usage of VCPU_SSHOTTMR_future in Linux kernel was removed by:
c06b6d70 xen/x86: don't lose event interrupts
Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20240619104015.30477-1-frediano.ziglio@cloud.comSigned-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/time.c

@@ -30,7 +30,7 @@
 #include "xen-ops.h"
 
 /* Minimum amount of time until next clock event fires */
-#define TIMER_SLOP	100000
+#define TIMER_SLOP	1
 
 static u64 xen_sched_clock_offset __read_mostly;