Correct disassembly of dot product instructions.

Dot products deviate from the normal disassembly rules for lane indexed
instruction. Their canonical representation is in the form of:

v0.2s, v0.8b, v0.4b[0] instead of v0.2s, v0.8b, v0.b[0] to try to denote
that these instructions select 4x 1 byte elements instead of a single 1 byte
element.

Previously we were disassembling them following the normal rules, this patch
corrects the disassembly.

gas/

	PR gas/22559
	* config/tc-aarch64.c (vectype_to_qualifier): Support AARCH64_OPND_QLF_S_4B.
	* gas/testsuite/gas/aarch64/dotproduct.d: Update disassembly.

include/

	PR gas/22559
	* aarch64.h (aarch64_opnd_qualifier): Add AARCH64_OPND_QLF_S_4B.

opcodes/

	PR gas/22559
	* aarch64-asm.c (aarch64_ins_reglane): Change AARCH64_OPND_QLF_S_B to
	AARCH64_OPND_QLF_S_4B
	* aarch64-dis.c (aarch64_ext_reglane): Change AARCH64_OPND_QLF_S_B to
	AARCH64_OPND_QLF_S_4B
	* aarch64-opc.c (aarch64_opnd_qualifiers): Add 4b variant.
	* aarch64-tbl.h (QL_V2DOT): Change S_B to S_4B.

Change-Id: Ie80d878ceaeaca281f85583e77e4e367e2a909ea