RFR: 8303955: RISC-V: Factor out the tmp parameter from copy_memory and copy_memory_v

[Fei Yang]

On Fri, 10 Mar 2023 09:12:25 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

> The call site of `copy_memory` and `copy_memory_v` always use `t0` as tmp register, so we can factor the tmp parameter out.
> 
> Testing:
> 
> - [x] tier1 tests on Unmatched board (release build with `-XX:-UseRVV`)
> - [x] hotspot_tier1 and jdk_tier1 on QEMU (release build with `-XX:+UseRVV`)

Looks fine. Thanks.

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Marked as reviewed by fyang (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12969