kernel: Bluetooth: hci_{ldisc,serdev}: check percpu_init_rwsem() failure

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hcildisc,serdev: check percpuinitrwsem failure syzbot is reporting NULL pointer dereference at hciuartttyclose 1, for rcusyncenter is called without rcusyncinit due to hciuartttyopen ignoring percpuinitrwsem failure...