AArch64: Annotate SVE instructions with new instruction attribute.

AArch64: Annotate SVE instructions with new instruction attribute.

In this patch, we add the new instruction attribute "sve_type" and use it to
annotate the SVE instructions in aarch64-sve.md and aarch64-sve2.md. This
allows us to use instruction attributes to group instructions into dispatch
groups for dispatch scheduling. While there had already been fine-grained
annotation of scalar and neon instructions (mostly using the "type"-attribute),
annotation was missing for SVE instructions.

The values of the attribute "sve_type" are comparatively coarse-grained, but
fulfill the two criteria we aimed for with regard to dispatch scheduling:
- the annotation allows the definition of CPU-specific high-level attributes
  mapping instructions to dispatch constraints
- the annotation is by itself CPU-independent and consistent, i.e. all
  instructions fulfilling certain criteria are tagged with the corresponding
  value

The patch was bootstrapped and tested on aarch64-linux-gnu, no regression.

Signed-off-by: Jennifer Schmitz <jschmitz@nvidia.com>
gcc/ChangeLog:

	* config/aarch64/aarch64-sve.md: Annotate instructions with
	attribute sve_type.
	* config/aarch64/aarch64-sve2.md: Likewise.
	* config/aarch64/aarch64.md (sve_type): New attribute sve_type.
	* config/aarch64/iterators.md (sve_type_unspec): New int attribute.
	(sve_type_int): New code attribute.
	(sve_type_fp): New int attribute.