net: mdio: fix undefined behavior in bit shift for __mdiobus_register

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

net: mdio: fix undefined behavior in bit shift for __mdiobus_register

Shifting signed 32-bit value by 31 bits is undefined, so changing

significant bit to unsigned. The UBSAN warning calltrace like below:

UBSAN: shift-out-of-bounds in drivers/net/phy/mdio_bus.c:586:27

left shift of 1 by 31 places cannot be represented in type 'int'

Call Trace:

<TASK>

dump_stack_lvl+0x7d/0xa5

dump_stack+0x15/0x1b

ubsan_epilogue+0xe/0x4e

__ubsan_handle_shift_out_of_bounds+0x1e7/0x20c

__mdiobus_register+0x49d/0x4e0

fixed_mdio_bus_init+0xd8/0x12d

do_one_initcall+0x76/0x430

kernel_init_freeable+0x3b3/0x422

kernel_init+0x24/0x1e0

ret_from_fork+0x1f/0x30

</TASK>