aarch64: Add support for unpacked SVE ADR

aarch64: Add support for unpacked SVE ADR

This patch extends the ADR patterns to handle unpacked vectors.
They would work with both elements and containers, but since
the instructions only support .s and .d, we get more coverage
by using containers.

gcc/
	* config/aarch64/iterators.md (SVE_24I): New iterator.
	* config/aarch64/aarch64-sve.md (*aarch64_adr<mode>_shift): Extend from
	SVE_FULL_SDI to SVE_24I.  Use containers rather than elements.

gcc/testsuite/
	* gcc.target/aarch64/sve/adr_6.c: New test.