libswscale: remove unnecessary direct #if LIBSWSCALE_VERSION_MAJOR

SWS_CPU_CAPS are deprecated and slated to removed with libswscale major
version 3. No need to provide a SWS_CPU_CAPS_MMX2 as backward
compatibility define under the same explicit condition.

libswscale/swscale.h

@@ -85,9 +85,7 @@ const char *swscale_license(void);
  */
 #define SWS_CPU_CAPS_MMX      0x80000000
 #define SWS_CPU_CAPS_MMXEXT   0x20000000
-#if LIBSWSCALE_VERSION_MAJOR < 3
 #define SWS_CPU_CAPS_MMX2     0x20000000
-#endif
 #define SWS_CPU_CAPS_3DNOW    0x40000000
 #define SWS_CPU_CAPS_ALTIVEC  0x10000000
 #define SWS_CPU_CAPS_BFIN     0x01000000