target/loongarch: Add sc.q instructions

target/loongarch: Add sc.q instructions

Add the sc.q instruction in LoongArch v1.1, guarded by CPUCFG2.SCQ. It
is implemented by reading 128bit data (llval + llval_high) in ll.d when
aligned to 16B boundary, and cmpxchg 128bit in sc.q. If ld.d
matches the higher part of the 128bit, its data is taken from
llval_high.

Expected assembly sequence:

ll.d lo, base, 0
ld.d hi, base, 8
sc.q lo, hi, base

Signed-off-by: Jiajie Chen <c@jia.je>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>