kernel: Add missing kernel config symbol

Add CONFIG_DW_DMAC_PCI

Signed-off-by: Florian Fainelli <[email protected]>

target/linux/generic/config-4.4

@@ -978,6 +978,7 @@ CONFIG_DUMMY_CONSOLE_ROWS=25
 # CONFIG_DWMAC_SOCFPGA is not set
 # CONFIG_DWMAC_STI is not set
 # CONFIG_DW_DMAC is not set
+# CONFIG_DW_DMAC_PCI is not set
 # CONFIG_DW_WATCHDOG is not set
 # CONFIG_DYNAMIC_DEBUG is not set
 # CONFIG_E100 is not set