board: ls1046ardb: force PCI device enumeration

Commit 045ecf89 ("configs: enable DM_ETH support for LS1046ARDB")
resulted in the PCI bus no longer being implicitly enumerated.

However, this is necessary for the fdt pcie fixups to work.

Therefore, similar to commit 8b6558bd ("board: ls1088ardb:
transition to DM_ETH"), pci_init() is now called in the board_init()
routine when CONFIG_DM_ETH is active.

Signed-off-by: Martin Schiller <ms@dev.tdt.de>
CC: Priyanka Jain <priyanka.jain@nxp.com>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>