asm_tests: FEXCore: Fix initial PF flag value

unittests/ASM/FEX_bugs/InitialPFFlag.asm

@@ -0,0 +1,18 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x202"
+  }
+}
+%endif
+
+mov rsp, 0xe0000010
+
+pushfq
+pop rax
+
+; Mask out only the flags we care about (ignore undefined bits)
+; Keep: CF(0), PF(2), AF(4), ZF(6), SF(7), IF(9), DF(10), OF(11), reserved(1)
+and rax, 0xED7
+
+hlt