x86/hvm: Use PUSH_AND_CLEAR_GPRS in preference to SAVE_ALL

PUSH_AND_CLEAR_GPRS is shorter than SAVE_ALL in terms of emitted code.
SAVE_ALL hides a CLD instruction which is not needed anywhere here.

 * VMX VMExit always clears flags.  VMX VMentry failure never switched away
   from the host flags, so they're still good.
 * SVM VMRUN always saves and restores the host flags.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/hvm/svm/entry.S

@@ -89,7 +89,7 @@ __UNLIKELY_END(nsvm_hap)
 
         vmrun
 
-        SAVE_ALL
+        PUSH_AND_CLEAR_GPRS
 
         GET_CURRENT(bx)
 

xen/arch/x86/hvm/vmx/entry.S

@@ -22,7 +22,7 @@
 #include <asm/page.h>
 
 FUNC(vmx_asm_vmexit_handler)
-        SAVE_ALL
+        PUSH_AND_CLEAR_GPRS
 
         mov  %cr2,%rax
         GET_CURRENT(bx)
@@ -157,7 +157,7 @@ UNLIKELY_END(realmode)
 
 .Lvmx_vmentry_fail:
         sti
-        SAVE_ALL
+        PUSH_AND_CLEAR_GPRS
 
         /*
          * SPEC_CTRL_ENTRY notes