[rs6000] Fix ambiguous .md attribute uses

[rs6000] Fix ambiguous .md attribute uses

This patch is part of a series that fixes ambiguous attribute
uses in .md files, i.e. cases in which attributes didn't use
<ITER:ATTR> to specify an iterator, and in which <ATTR> could
have different values depending on the iterator chosen.

No behavioural change -- produces the same code as before except
for formatting and line numbers.

2019-07-16  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/rs6000/rs6000.md (*mov<mode>_update1): Explicitly
	use <SFDF:mode>, <SFDF:MODE>, <SFDF:Ff> and <SFDF:bits> rather than
	leaving the choice between SFDF and P implicit.
	(*mov<mode>_update2): Likewise.
	(*cmp<IBM128:mode>_internal2): Explicitly use <IBM128:MODE>
	rather than leaving the choice betweem IBM128 and GPR implicit.
	(*fix<uns>_trunc<IEEE128:mode><QHSI:mode>2_mem): Explicitly use
	<IEEE128:MODE> rather than leaving the choice between IEEE128 and
	QHSI implicit.
	(AltiVec define_peephole2s): Explicitly use <ALTIVEC_DFORM:MODE>
	rather than leaving the choice between ALTIVEC_DFORM and P implicit.
	* config/rs6000/vsx.md
	(*vsx_ext_<VSX_EXTRACT_I:VS_scalar>_fl_<FL_CONV:mode>)
	(*vsx_ext_<VSX_EXTRACT_I:VS_scalar>_ufl_<FL_CONV:mode>): Explicitly
	use <FL_CONV:VSisa> rather than leaving the choice between FL_CONV
	and VSX_EXTRACT_I implicit.

From-SVN: r273509