genirq: Simplify the checks for irq_set_percpu_devid_partition()

Since whether desc is NULL or desc->percpu_enabled is true, it returns
-EINVAL, check them together, and assign desc->percpu_affinity using a
ternary to simplify the code.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240417085356.3785381-1-ruanjinjie@huawei.com