locking/pvqspinlock: Correct the type of "old" variable in pv_kick_node()

"enum vcpu_state" is not compatible with "u8" type for all targets,
resulting in:

error: initialization of 'u8 *' {aka 'unsigned char *'} from incompatible pointer type 'enum vcpu_state *'

for LoongArch. Correct the type of "old" variable to "u8".

Fixes: fea0e18 ("locking/pvqspinlock: Use try_cmpxchg() in qspinlock_paravirt.h")
Closes: https://lore.kernel.org/lkml/[email protected]/
Reported-by: Bibo Mao <[email protected]>
Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Waiman Long <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: ubizjak

kernel/locking/qspinlock_paravirt.h

@@ -357,7 +357,7 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
 static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
 {
 	struct pv_node *pn = (struct pv_node *)node;
-	enum vcpu_state old = vcpu_halted;
+	u8 old = vcpu_halted;
 	/*
 	 * If the vCPU is indeed halted, advance its state to match that of
 	 * pv_wait_node(). If OTOH this fails, the vCPU was running and will