riscv: Make sure toolchain supports zba before using zba instructions

riscv: Make sure toolchain supports zba before using zba instructions

Old toolchain like gcc 8.5.0 does not support zba, so we must check that
the toolchain supports this extension before using it in the kernel.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202503281836.8pntHm6I-lkp@intel.com/
Link: https://lore.kernel.org/r/20250328115422.253670-1-alexghiti@rivosinc.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>