SVE Intrinsics: Change return type of redirect_call to gcall.

SVE Intrinsics: Change return type of redirect_call to gcall.

As suggested in the review of
https://gcc.gnu.org/pipermail/gcc-patches/2024-July/657474.html,
this patch changes the return type of gimple_folder::redirect_call from
gimple * to gcall *. The motivation for this is that so far, most callers of
the function had been casting the result of the function to gcall. These
call sites were updated.

The patch was bootstrapped and regtested on aarch64-linux-gnu, no regression.
OK for mainline?

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

	* config/aarch64/aarch64-sve-builtins.cc
	(gimple_folder::redirect_call): Update return type.
	* config/aarch64/aarch64-sve-builtins.h: Likewise.
	* config/aarch64/aarch64-sve-builtins-sve2.cc (svqshl_impl::fold):
	Remove cast to gcall.
	(svrshl_impl::fold): Likewise.