[PATCH][GAS] RISC-V: Fix missing initialization of riscv_csr_extra structs

[Jim Wilson]

On Wed, May 27, 2020 at 9:35 AM Simon Cook <simon.cook@embecosm.com> wrote:
> The next pointer of struct riscv_csr_extra was not always initilized
> to NULL or a valid pointer, causing the assembler to attempt to read
> through an uninitialized pointer on startup.

Thanks.  Committed.

Jim