ci/docker: bump risc-v toolchain

[shtirlic]

Summary

Bump risc-v toolchain to 15.2.0-1
Update RISC-V gcc toolchain to recent version

Impact

Support additional RISC-V extensions in updated binutils

* Add support for RISC-V standard extensions,
  Zicfiss v1.0, Zicfilp v1.0, Zcmp v1.0 (cm.mva01s and cm.mvsa01 instructions),
  Zcmt v1.0, Smrnmi v1.0, S[sm]dbltrp v1.0 and S[sm]ctr v1.0 (replaced the
  dropped sfence.vm encoding since privileged spec v1.10).

* Add support for RISC-V vendor extensions,
  CORE-V, xcvbitmanip v1.0 and xcvsimd v1.0.
  SiFive, xsfvqmaccdod v1.0, xsfvqmaccqoqv1.0 and xsfvfnrclipxfqf v1.0.

Testing

rp2350-rv target compilation with Zcmp enabled

[lupyuen]

For future changes to the Docker Image: Please contact @simbit18 or myself for Docker Testing Instructions. Thanks!

The breaking changes have been rolled back:

• ci/docker: bump risc-v toolchain gcc14 #19035