aarch64: Remove SME2.1 forms of LUTI2/4

aarch64: Remove SME2.1 forms of LUTI2/4

I was over-eager when adding support for strided SME2 instructions
and accidentally included forms of LUTI2 and LUTI4 that are only
available with SME2.1, not SME2.  This patch removes them for now.
We're planning to add proper support for SME2.1 in the GCC 15
timeframe.

Sorry for the blunder :(

gcc/
	* config/aarch64/aarch64.md (stride_type): Remove luti_consecutive
	and luti_strided.
	* config/aarch64/aarch64-sme.md
	(@aarch64_sme_lut<LUTI_BITS><mode>): Remove stride_type attribute.
	(@aarch64_sme_lut<LUTI_BITS><mode>_strided2): Delete.
	(@aarch64_sme_lut<LUTI_BITS><mode>_strided4): Likewise.
	* config/aarch64/aarch64-early-ra.cc (is_stride_candidate)
	(early_ra::maybe_convert_to_strided_access): Remove support for
	strided LUTI2 and LUTI4.

gcc/testsuite/
	* gcc.target/aarch64/sme/strided_1.c (test5): Remove.