[test][LoongArch] Add -mattr=+d option. NFC

Because most of tests assume target-abi=`lp64d`, adding the
corresponding feature is reasonable.

rg -l loongarch -g '!*.s' | xargs sed -i '/mtriple=loongarch/ {/-mattr=/!{/target-abi/! s/mtriple=loongarch.. /&-mattr=+d /}}'