genirq/matrix: Fix kernel doc warnings for irq_matrix_alloc_managed()

Describe the arguments correctly.

Fixes the following W=1 kernel build warning(s):

kernel/irq/matrix.c:287: warning: Function parameter or
 member 'msk' not described in 'irq_matrix_alloc_managed'
kernel/irq/matrix.c:287: warning: Function parameter or
 member 'mapped_cpu' not described in 'irq_matrix_alloc_managed'
kernel/irq/matrix.c:287: warning: Excess function
 parameter 'cpu' description in 'irq_matrix_alloc_managed'

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210605063413.684085-1-libaokun1@huawei.com