gpio: xilinx: Convert gpio_lock to raw spinlock

In the Linux kernel, the following vulnerability has been resolved:

gpio: xilinx: Convert gpio_lock to raw spinlock

irq_chip functions may be called in raw spinlock context. Therefore, we
must also use a raw spinlock for our own internal locking.

This fixes the following lockdep splat:

[ 5.349336] =============================
[ 5.353349] [ BUG: Invalid wait context ]
[ 5.357361] 6.13.0-rc5+ #69 Tainted: G W
[ 5.363031] -----------------------------
[ 5.367045] kworker/u17:1/44 is trying to lock:
[ 5.371587] ffffff88018b02c0 (&chip->gpio_lock){....}-{3:3}, at: xgpio_irq_unmask (drivers/gpio/gpio-xilinx.c:433 (discriminator 8))
[ 5.380079] other info that might help us debug this:
[ 5.385138] context-{5:5}
[ 5.387762] 5 locks held by kworker/u17:1/44:
[ 5.392123] #0: ffffff8800014958 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3204)
[ 5.402260] #1: ffffffc082fcbdd8 (deferred_probe_work){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3205)
[ 5.411528] #2: ffffff880172c900 (&dev->mutex){....}-{4:4}, at: __device_attach (drivers/base/dd.c:1006)
[ 5.419929] #3: ffffff88039c8268 (request_class#2){+.+.}-{4:4}, at: __setup_irq (kernel/irq/internals.h:156 kernel/irq/manage.c:1596)
[ 5.428331] #4: ffffff88039c80c8 (lock_class#2){....}-{2:2}, at: __setup_irq (kernel/irq/manage.c:1614)
[ 5.436472] stack backtrace:
[ 5.439359] CPU: 2 UID: 0 PID: 44 Comm: kworker/u17:1 Tainted: G W 6.13.0-rc5+ #69
[ 5.448690] Tainted: [W]=WARN
[ 5.451656] Hardware name: xlnx,zynqmp (DT)
[ 5.455845] Workqueue: events_unbound deferred_probe_work_func
[ 5.461699] Call trace:
[ 5.464147] show_stack+0x18/0x24 C
[ 5.467821] dump_stack_lvl (lib/dump_stack.c:123)
[ 5.471501] dump_stack (lib/dump_stack.c:130)
[ 5.474824] __lock_acquire (kernel/locking/lockdep.c:4828 kernel/locking/lockdep.c:4898 kernel/locking/lockdep.c:5176)
[ 5.478758] lock_acquire (arch/arm64/include/asm/percpu.h:40 kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851 kernel/locking/lockdep.c:5814)
[ 5.482429] _raw_spin_lock_irqsave (include/linux/spinlock_api_smp.h:111 kernel/locking/spinlock.c:162)
[ 5.486797] xgpio_irq_unmask (drivers/gpio/gpio-xilinx.c:433 (discriminator 8))
[ 5.490737] irq_enable (kernel/irq/internals.h:236 kernel/irq/chip.c:170 kernel/irq/chip.c:439 kernel/irq/chip.c:432 kernel/irq/chip.c:345)
[ 5.494060] __irq_startup (kernel/irq/internals.h:241 kernel/irq/chip.c:180 kernel/irq/chip.c:250)
[ 5.497645] irq_startup (kernel/irq/chip.c:270)
[ 5.501143] __setup_irq (kernel/irq/manage.c:1807)
[ 5.504728] request_threaded_irq (kernel/irq/manage.c:2208)