lan78xx: Fix ladv/radv error handling in lan78xx_link_reset()

net/usb/lan78xx.c: In function ‘lan78xx_link_reset’:
net/usb/lan78xx.c:1107: warning: comparison is always false due to limited range of data type
net/usb/lan78xx.c:1111: warning: comparison is always false due to limited range of data type

Assigning return values that can be negative error codes to "u16"
variables makes them positive, ignoring the errors.  Hence use "int"
instead.

Drop the "unlikely"s (unlikely considered harmful) and propagate the
actual error values instead of overriding them to -EIO while we're at
it.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>