riscv: Do not fail to build on byte/halfword operations with Zawrs

riscv does not have lr instructions on byte and halfword but the
qspinlock implementation actually uses such atomics provided by the
Zabha extension, so those sizes are legitimate.

Then instead of failing to build, just fallback to the !Zawrs path.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20241103145153.105097-3-alexghiti@rivosinc.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>