swscale: x86: Drop pointless _mmx suffix from filenames

The files do not contain only MMX code.

libswscale/x86/Makefile

@@ -1,8 +1,8 @@
 OBJS-$(CONFIG_XMM_CLOBBER_TEST) += x86/w64xmmtest.o
 
 MMX-OBJS                        += x86/rgb2rgb.o                        \
-                                   x86/swscale_mmx.o                    \
-                                   x86/yuv2rgb_mmx.o                    \
+                                   x86/swscale.o                        \
+                                   x86/yuv2rgb.o                        \
 
 YASM-OBJS                       += x86/input.o                          \
                                    x86/output.o                         \