i386: Fix up last -masm=intel operand of vcvthf82ph [PR124349]

gas expects for this instruction
vcvthf82ph      xmm30, QWORD PTR [r9]
vcvthf82ph      ymm30, XMMWORD PTR [r9]
vcvthf82ph      zmm30, YMMWORD PTR [r9]
i.e. the memory size is half of the dest register size.
We currently emit it for the last 2 forms but emit XMMWORD PTR
for the first one too.  So, we need %q1 for V8HF and for V16HF/V32HF
can either use just %1 or %x1/%t1.  There is no define_mode_attr
that would provide those, so I've added one just for this insn.

2026-03-05  Jakub Jelinek  <jakub@redhat.com>

	PR target/124349
	* config/i386/sse.md (iptrssebvec_2): New define_mode_attr.
	(cvthf82ph<mode><mask_name>): Use it for -masm=intel input
	operand.

	* gcc.target/i386/avx10_2-pr124349-2.c: New test.