x264/x262: purge obsolete disable-SIMD bits

a call made to x264_param_default[_mpeg2]() triggers cpu feature detection built into the x262/x264 lib, setting up the default value of the cpu flags 'param' attribute. the block of code deleted here pointlessly tried to subsequently remove a certain subset of flags from this where the vlc detection found those features to not be available.

this dates back to before VLC v1.2 when we had core options that gave users a means of disabling use of individual SIMD variants - this block of code would apply such user choices to the use of the x262/x264 lib.

those options were removed in 1081b213 for v1.2, but blocks of code like this were left behind. some adjustments to the cpu detection code were done for v1.3, which touched these code blocks, but seems to not have involved evaluating their necessity.

without those old options, this block of code is utterly pointless, achieving nothing.