LoongArch: Remove several syntactic sugar macros for branches

mainline inclusion
from mainline-v5.19
commit ab6e57a6
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB


CVE: NA

--------------------------------

These syntactic sugars have been supported by upstream binutils from the
beginning, so no need to patch them locally.

Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>