linux-yocto/6.12: riscv tune fragments

linux-yocto/6.12: riscv tune fragments

Integrating the following commit(s) to linux-yocto/.:

1/1 [
    Author: Mark Hatle
    Email: mark.hatle@amd.com
    Subject: arch/riscv/tunes: Implement RISC-V ISA selection
    Date: Wed, 18 Jun 2025 18:20:08 -0500

    You need to first clear (risc-isa-clear) the defaults, and then apply the
    ISA components starting with the base ISA and extensions (riscv-isa-...).

    Only ISA extensions available in TUNE_FEATURES are currently
    implemented.

    Signed-off-by: Mark Hatle <mark.hatle@amd.com>
    Signed-off-by: Mark Hatle <mark.hatle@kernel.crashing.org>
    Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
]

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 2080c8f215ca71d526c39a87d3307e4c65476a39)
Signed-off-by: Steve Sakoman <steve@sakoman.com>