[Bug target/107731] loongarch Operand Modifiers are not documented

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107731

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
MIPS nor RISCV does not define a %c either.