net: smc911x: Fix min() use in debug code

If ENABLE_SMC_DEBUG_PKTS=1:

    drivers/net/ethernet/smsc/smc911x.c: In function ‘smc911x_hardware_send_pkt’:
    include/linux/minmax.h:20:28: error: comparison of distinct pointer types lacks a cast [-Werror]
       20 |  (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
	  |                            ^~
    drivers/net/ethernet/smsc/smc911x.c:483:17: note: in expansion of macro ‘min’
      483 |  PRINT_PKT(buf, min(len, 64));

Fix this by making the constant unsigned, to match the type of "len".
While at it, replace the other missed ternary operator by min(), too.

Convert the dummy PRINT_PKT() from a macro to a static inline function,
to catch mistakes like this without having to enable debug options
manually.

Fixes: 5ff0348b

 ("net: smc911x: replace ternary operator with min()")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: David S. Miller <davem@davemloft.net>