swscale/x86/hscale_fast_bilinear_simd: Fix variable names in comments

Found-by: Nick Lewycky <nlewycky@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/x86/hscale_fast_bilinear_simd.c

@@ -329,8 +329,8 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
         CALL_MMXEXT_FILTER_CODE
         CALL_MMXEXT_FILTER_CODE
         "xor          %%"REG_a", %%"REG_a"  \n\t" // i
-        "mov                 %5, %%"REG_c"  \n\t" // src
-        "mov                 %6, %%"REG_D"  \n\t" // buf2
+        "mov                 %5, %%"REG_c"  \n\t" // src2
+        "mov                 %6, %%"REG_D"  \n\t" // dst2
         PREFETCH"   (%%"REG_c")             \n\t"
         PREFETCH" 32(%%"REG_c")             \n\t"
         PREFETCH" 64(%%"REG_c")             \n\t"