x86: yadif: Mark mmxext optimizations as such

The yadif mmx optimizations contain the pmaxsw and pmaxub mmxext
instructions, causing sigills on CPUs that do not support mmxext.

libavfilter/x86/yadif.c

@@ -45,9 +45,9 @@ DECLARE_ASM_CONST(16, const xmm_reg, pw_1) = {0x0001000100010001ULL, 0x000100010
 #undef COMPILE_TEMPLATE_SSE
 #endif
 
-#if HAVE_MMX
+#if HAVE_MMX2
 #undef RENAME
-#define RENAME(a) a ## _mmx
+#define RENAME(a) a ## _mmx2
 #include "yadif_template.c"
 #endif
 
@@ -58,9 +58,9 @@ av_cold void ff_yadif_init_x86(YADIFContext *yadif)
     int cpu_flags = av_get_cpu_flags();
 
 #if HAVE_INLINE_ASM
-#if HAVE_MMX
-    if (cpu_flags & AV_CPU_FLAG_MMX)
-        yadif->filter_line = yadif_filter_line_mmx;
+#if HAVE_MMX2
+    if (cpu_flags & AV_CPU_FLAG_MMX2)
+        yadif->filter_line = yadif_filter_line_mmx2;
 #endif
 #if HAVE_SSE
     if (cpu_flags & AV_CPU_FLAG_SSE2)