coresight: etm4x: Change sdei_list_lock type

When start with preempt-rt kernel, the following problem occurs when
executing cpu-hotplug. Replace spinlock in struct etmv4_drvdata with
a raw_spinlock to fix.

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 19, name: migration/1
1 lock held by migration/1/19:
 #0: ffff00014d8f9930 (&drvdata->spinlock){....}-{0:0}, at: etm4_dying_cpu+0x38/0x70
irq event stamp: 14178
hardirqs last  enabled at (14177): [<ffff800010f51530>] _raw_spin_unlock_irq+0x50/0xc0
hardirqs last disabled at (14178): [<ffff800010163998>] multi_cpu_stop+0x168/0x1b0
softirqs last  enabled at (0): [<ffff80001003dd10>] copy_process+0x350/0x1170
softirqs last disabled at (0): [<0000000000000000>] 0x0
Preemption disabled at:
[<ffff800010163048>] cpu_stopper_thread+0xa4/0x13c
CPU: 1 PID: 19 Comm: migration/1 Not tainted 5.10.79-rt54-yocto-preempt-rt #1
Hardware name: Marvell OcteonTX CN96XX board (DT)
Stopper: multi_cpu_stop+0x0/0x1b0 <- 0x0
Call trace:
 dump_backtrace+0x0/0x1e0
 show_stack+0x24/0x30
 dump_stack+0xec/0x154
 ___might_sleep+0x17c/0x1f0
 rt_spin_lock+0x74/0x100
 etm4_dying_cpu+0x38/0x70
 cpuhp_invoke_callback+0xb0/0x280
 take_cpu_down+0x94/0xf0
 multi_cpu_stop+0xac/0x1b0
 cpu_stopper_thread+0xac/0x13c
 smpboot_thread_fn+0x298/0x340
 kthread+0x174/0x180
 ret_from_fork+0x10/0x18

Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>