riscv: qspinlock: Fixup _Q_PENDING_LOOPS definition

When CONFIG_RISCV_QUEUED_SPINLOCKS=y, the _Q_PENDING_LOOPS
definition is missing. Add the _Q_PENDING_LOOPS definition for
pure qspinlock usage.

Fixes: ab83647f ("riscv: Add qspinlock support")
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20241215135252.201983-1-guoren@kernel.org


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