drivers: net: xgene: Pre-initialize ret in xgene_enet_get_resources()

If CONFIG_ACPI=n:

    drivers/net/ethernet/apm/xgene/xgene_enet_main.c: In function ‘xgene_enet_get_resources’:
    drivers/net/ethernet/apm/xgene/xgene_enet_main.c:951: warning: ‘ret’ may be used uninitialized in this function

If the driver is bound to a legacy platform device, ret will contain
arbitrary data. If it is non-zero, it will be returned to the caller as
an error code.

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