Revert "PCI: armada8k: Add support for gpio controlled reset signal"

Revert commit 3d71746c ("PCI: armada8k: Add support for gpio controlled
reset signal").

That commit breaks boot on Macchiatobin board when a Mellanox NIC is
present in the PCIe slot.

It turns out that full reset cycle requires first comphy serdes
initialization. Reset signal toggle without comphy initialization makes
access to PCI configuration registers stall indefinitely. U-Boot toggles
the Macchiatobin PCIe reset line already at boot, after initializing the
comphy serdes.

So while commit 3d71746c ("PCI: armada8k: Add support for gpio controlled
reset signal") enables PCIe on platforms that U-Boot does not touch the
reset line (like Clearfog GT-8K), it breaks PCIe (and boot) on the
Macchiatobin board.

Revert commit 3d71746c ("PCI: armada8k: Add support for gpio controlled
reset signal") entirely to fix the Macchiatobin regression.

Reported-by: Sven Auhagen <sven.auhagen@voleatech.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>