cpufreq: Init completion before kobject_init_and_add()

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

cpufreq: Init completion before kobject_init_and_add()

In cpufreq_policy_alloc(), it will call uninitialed completion in

cpufreq_sysfs_release() when kobject_init_and_add() fails. And

that will cause a crash such as the following page fault in complete:

BUG: unable to handle page fault for address: fffffffffffffff8

[..]

RIP: 0010:complete+0x98/0x1f0

[..]

Call Trace:

kobject_put+0x1be/0x4c0

cpufreq_online.cold+0xee/0x1fd

cpufreq_add_dev+0x183/0x1e0

subsys_interface_register+0x3f5/0x4e0

cpufreq_register_driver+0x3b7/0x670

acpi_cpufreq_init+0x56c/0x1000 [acpi_cpufreq]

do_one_initcall+0x13d/0x780

do_init_module+0x1c3/0x630

load_module+0x6e67/0x73b0

__do_sys_finit_module+0x181/0x240

do_syscall_64+0x35/0x80

entry_SYSCALL_64_after_hwframe+0x63/0xcd