net: ethernet: renesas: Fix return type in rswitch_etha_wait_link_verification()

The rswitch_etha_wait_link_verification() is supposed to return zero
on success or negative error codes.  Unfortunately it is declared as a
bool so the caller treats everything as success.

Fixes: 3590918b ("net: ethernet: renesas: Add support for "Ethernet Switch"")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/Y3OPo6AOL6PTvXFU@kiliSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/renesas/rswitch.c

@@ -920,7 +920,7 @@ static void rswitch_etha_write_mac_address(struct rswitch_etha *etha, const u8 *
 		  etha->addr + MRMAC1);
 }
 
-static bool rswitch_etha_wait_link_verification(struct rswitch_etha *etha)
+static int rswitch_etha_wait_link_verification(struct rswitch_etha *etha)
 {
 	iowrite32(MLVC_PLV, etha->addr + MLVC);