ath79: remove obsolete OF PCI related config symbols

Those symbols were removed in kernel 4.16:

 commit 4670d610d59233b017a6ea1fa25bbf06dabbff42
 Author:     Rob Herring <[email protected]>

    PCI: Move OF-related PCI functions into PCI core

Fixes: FS#2588
Signed-off-by: Petr Štetiar <[email protected]>

target/linux/ath79/config-4.19

@@ -179,7 +179,6 @@ CONFIG_NO_GENERIC_PCI_IOPORT_MAP=y
 CONFIG_NVMEM=y
 CONFIG_OF=y
 CONFIG_OF_ADDRESS=y
-CONFIG_OF_ADDRESS_PCI=y
 CONFIG_OF_EARLY_FLATTREE=y
 CONFIG_OF_FLATTREE=y
 CONFIG_OF_GPIO=y
@@ -187,8 +186,6 @@ CONFIG_OF_IRQ=y
 CONFIG_OF_KOBJ=y
 CONFIG_OF_MDIO=y
 CONFIG_OF_NET=y
-CONFIG_OF_PCI=y
-CONFIG_OF_PCI_IRQ=y
 CONFIG_PCI=y
 CONFIG_PCI_AR71XX=y
 CONFIG_PCI_AR724X=y