vme: Fix error not catched in fake_init()

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

vme: Fix error not catched in fake_init()

In fake_init(), __root_device_register() is possible to fail but it's

ignored, which can cause unregistering vme_root fail when exit.

general protection fault,

probably for non-canonical address 0xdffffc000000008c

KASAN: null-ptr-deref in range [0x0000000000000460-0x0000000000000467]

RIP: 0010:root_device_unregister+0x26/0x60

Call Trace:

<TASK>

__x64_sys_delete_module+0x34f/0x540

do_syscall_64+0x38/0x90

entry_SYSCALL_64_after_hwframe+0x63/0xcd

Return error when __root_device_register() fails.