linux-yocto/6.12: riscv: Enable TUNE_FEATURES based KERNEL_FEATURES

linux-yocto/6.12: riscv: Enable TUNE_FEATURES based KERNEL_FEATURES

Allow the risc-v TUNE_FEATURES to select specific ISA (kconfig) selections
in the kernel config via config fragments selected by KERNEL_FEATURES.

This allows the following items to be selected dynamically:

    CONFIG_ARCH_RV32I
    CONFIG_ARCH_RV64I
    CONFIG_FPU
    CONFIG_RISCV_ISA_C
    CONFIG_RISCV_ISA_V
    CONFIG_RISCV_ISA_ZBB
    CONFIG_RISCV_ISA_ZICBOM
    CONFIG_RISCV_ISA_ZICBOZ
    CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI

Note: Some ISA options, such as CONFIG_RISCV_ISA_C may be reenabled by other
options such as CONFIG_EFI.  This is properly reported by the configuration
tooling.

Signed-off-by: Mark Hatle <mark.hatle@amd.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 45a1b5aa6abc9007d0d87efc2d740b5564a209dd)
Signed-off-by: Steve Sakoman <steve@sakoman.com>