rs6000: lxsdux / stxsdux do not exist

rs6000: lxsdux / stxsdux do not exist

Our md files refer to {l,st}xsd%U<n>x, but no {l,st}xsdux insns exist.
This patch removes the update forms.  All these use  constraint "Z"
which does not allow update form, so there is no practical difference.

	* config/rs6000/rs6000.md (*mov<mode>_hardfloat32): Remove %U from the
	lxsdx and stxsdx alternatives.
	(*mov<mode>_hardfloat64): Ditto.
	* config/rs6000/vsx.md (*vsx_extract_<mode>_store): Ditto.

From-SVN: r264064