riscv: Provide all alternative macros all the time

riscv: Provide all alternative macros all the time

We need to provide all six forms of the alternative macros
(ALTERNATIVE, ALTERNATIVE_2, _ALTERNATIVE_CFG, _ALTERNATIVE_CFG_2,
__ALTERNATIVE_CFG, __ALTERNATIVE_CFG_2) for all four cases derived
from the two ifdefs (RISCV_ALTERNATIVE, __ASSEMBLY__) in order to
ensure all configs can compile. Define this missing ones and ensure
all are defined to consume all parameters passed.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202504130710.3IKz6Ibs-lkp@intel.com/
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250414120947.135173-2-ajones@ventanamicro.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>