net: smc911x: Clean up the status handling in smc911x_recv()

Invert the status handling logic in smc911x_recv(), to make the
function easier to read, no functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>