x86/EFI: also fill boot_tsc_stamp on the xen.efi boot path

Commit e3a379c35e ("x86/time: always count s_time from Xen boot")
introducing this missed adjusting this path as well.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>

xen/arch/x86/efi/efi-boot.h

@@ -8,6 +8,7 @@
 #include <asm/edd.h>
 #include <asm/microcode.h>
 #include <asm/msr.h>
+#include <asm/setup.h>
 
 static struct file __initdata ucode;
 static multiboot_info_t __initdata mbi = {
@@ -673,6 +674,8 @@ static void __init efi_arch_cpu(void)
     uint32_t eax = cpuid_eax(0x80000000);
     uint32_t *caps = boot_cpu_data.x86_capability;
 
+    boot_tsc_stamp = rdtsc();
+
     caps[cpufeat_word(X86_FEATURE_HYPERVISOR)] = cpuid_ecx(1);
 
     if ( (eax >> 16) == 0x8000 && eax > 0x80000000 )

xen/include/asm-x86/setup.h

@@ -10,6 +10,7 @@ extern char __2M_init_start[], __2M_init_end[];
 extern char __2M_rwdata_start[], __2M_rwdata_end[];
 
 extern unsigned long xenheap_initial_phys_start;
+extern uint64_t boot_tsc_stamp;
 
 void early_cpu_init(void);
 void early_time_init(void);