Port dotnet/coreclr#5821 to Linux (dotnet/coreclr#9347)

Commit migrated from dotnet/coreclr@e01f1e1

Author: qmfrederik

src/coreclr/src/vm/arm64/asmhelpers.S

@@ -286,7 +286,7 @@ WRITE_BARRIER_END JIT_CheckedWriteBarrier
 //
 WRITE_BARRIER_ENTRY JIT_WriteBarrier
     dmb  ST
-    str  x15, [x14], 8
+    str  x15, [x14]
 
     // Branch to Exit if the reference is not in the Gen0 heap
     //
@@ -312,6 +312,7 @@ LOCAL_LABEL(UpdateCardTable):
     mov  x12, 0xFF 
     strb w12, [x15]
 LOCAL_LABEL(Exit):
+    add  x14, x14, 8
     ret  lr  
 WRITE_BARRIER_END JIT_WriteBarrier