net: sfc: ef10: fix memory leak in efx_ef10_mtd_probe()

In the NIC ->probe() callback, ->mtd_probe() callback is called.
If NIC has 2 ports, ->probe() is called twice and ->mtd_probe() too.
In the ->mtd_probe(), which is efx_ef10_mtd_probe() it allocates and
initializes mtd partiion.
But mtd partition for sfc is shared data.
So that allocated mtd partition data from last called
efx_ef10_mtd_probe() will not be used.
Therefore it must be freed.
But it doesn't free a not used mtd partition data in efx_ef10_mtd_probe().

kmemleak reports:
unreferenced object 0xffff88811ddb0000 (size 63168):
  comm "systemd-udevd", pid 265, jiffies 4294681048 (age 348.586s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffffa3767749>] kmalloc_order_trace+0x19/0x120
    [<ffffffffa3873f0e>] __kmalloc+0x20e/0x250
    [<ffffffffc041389f>] efx_ef10_mtd_probe+0x11f/0x270 [sfc]
    [<ffffffffc0484c8a>] efx_pci_probe.cold.17+0x3df/0x53d [sfc]
    [<ffffffffa414192c>] local_pci_probe+0xdc/0x170
    [<ffffffffa4145df5>] pci_device_probe+0x235/0x680
    [<ffffffffa443dd52>] really_probe+0x1c2/0x8f0
    [<ffffffffa443e72b>] __driver_probe_device+0x2ab/0x460
    [<ffffffffa443e92a>] driver_probe_device+0x4a/0x120
    [<ffffffffa443f2ae>] __driver_attach+0x16e/0x320
    [<ffffffffa4437a90>] bus_for_each_dev+0x110/0x190
    [<ffffffffa443b75e>] bus_add_driver+0x39e/0x560
    [<ffffffffa4440b1e>] driver_register+0x18e/0x310
    [<ffffffffc02e2055>] 0xffffffffc02e2055
    [<ffffffffa3001af3>] do_one_initcall+0xc3/0x450
    [<ffffffffa33ca574>] do_init_module+0x1b4/0x700
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Fixes: 8127d661 ("sfc: Add support for Solarflare SFC9100 family")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://lore.kernel.org/r/20220512054709.12513-1-ap420073@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/sfc/ef10.c

@@ -3579,6 +3579,11 @@ static int efx_ef10_mtd_probe(struct efx_nic *efx)
 		n_parts++;
 	}
 
+	if (!n_parts) {
+		kfree(parts);
+		return 0;
+	}
+
 	rc = efx_mtd_add(efx, &parts[0].common, n_parts, sizeof(*parts));
 fail:
 	if (rc)