[JITLink][RISCV] Order EdgeKind_riscv the same way as relocations

There were basically four different orderings: one defined by the
relocations, one by the enum definition of EdgeKind_riscv, one for
mapping the enum values to their names, and one when mapping the
relocations to edge kinds and finally processing them. Chose the
ordering defined by the relocations in the riscv-elf-psabi-doc as
the canonical one.

Differential Revision: https://reviews.llvm.org/D140802