board: gdsys: a38x: Enable PCIe link 2 in spl_board_init()

board: gdsys: a38x: Enable PCIe link 2 in spl_board_init()

A385 controlcenterdc board does not use PCI DM properly and touches some
PCIe devices directly in its board code.

This controlcenterdc spl_board_init() function expects that PCIe link is
already initialized. Link itself is initialized in a38x serdes code but
this will change in future and link initialization will be postponed from
U-Boot SPL to proper U-Boot.

So explicitly enable PCIe link 2 in spl_board_init() function via
SoC Control Register 1 to not break this code by future changes. This board
has PCIe link 2 just x1, so no additional initialization (except enabling
PCIe port) is needed.

Signed-off-by: Pali Rohár <pali@kernel.org>