soc: xilinx: rename cpu_number1 to dummy_cpu_number

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

soc: xilinx: rename cpu_number1 to dummy_cpu_number

The per cpu variable cpu_number1 is passed to xlnx_event_handler as
argument "dev_id", but it is not used in this function. So drop the
initialization of this variable and rename it to dummy_cpu_number.
This patch is to fix the following call trace when the kernel option
CONFIG_DEBUG_ATOMIC_SLEEP is enabled:

BUG: sleeping function called from invalid context at include/linux/sched/mm.h:274
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0
preempt_count: 1, expected: 0
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0 #53
Hardware name: Xilinx Versal vmk180 Eval board rev1.1 (QSPI) (DT)
Call trace:
dump_backtrace+0xd0/0xe0
show_stack+0x18/0x40
dump_stack_lvl+0x7c/0xa0
dump_stack+0x18/0x34
__might_resched+0x10c/0x140
__might_sleep+0x4c/0xa0
__kmem_cache_alloc_node+0xf4/0x168
kmalloc_trace+0x28/0x38
__request_percpu_irq+0x74/0x138
xlnx_event_manager_probe+0xf8/0x298
platform_probe+0x68/0xd8