pci: imx: use reset-gpios if defined by device-tree

If reset-gpio is defined by device-tree use that if
CONFIG_PCIE_IMX_PERST_GPIO is not defined.

Note that after this the following boards which define
CONFIG_PCIE_IMX_PERST_GPIO in their board header file as well as their
device-tree should be able to remove CONFIG_PCIE_IMX_PERST_GPIO without
consequence:
 - mx6sabresd
 - mx6sxsabresd
 - novena
 - tbs2910
 - vining_2000

Note that the ge_bx50v3 board uses CONFIG_PCIE_IMX_PERST_GPIO and does
not have reset-gpios defined it it's pcie node in the dt thus removing
CONFIG_PCIE_IMX_PERST_GPIO globally can't be done until that board adds
reset-gpios.

Cc: Ian Ray <ian.ray@ge.com> (maintainer:GE BX50V3 BOARD)
Cc: Sebastian Reichel <sebastian.reichel@collabora.com> (maintainer:GE BX50V3 BOARD)
Cc: Fabio Estevam <festevam@gmail.com> (maintainer:MX6SABRESD BOARD)
Cc: Marek Vasut <marex@denx.de> (maintainer:NOVENA BOARD)
Cc: Soeren Moch <smoch@web.de> (maintainer:TBS2910 BOARD)
Cc: Silvio Fricke <open-source@softing.de> (maintainer:VINING_2000 BOARD)
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
diff --git a/arch/arm/include/asm/arch-mx6/sys_proto.h b/arch/arm/include/asm/arch-mx6/sys_proto.h
index 1e5fa1a..c49759a 100644
--- a/arch/arm/include/asm/arch-mx6/sys_proto.h
+++ b/arch/arm/include/asm/arch-mx6/sys_proto.h
@@ -7,6 +7,7 @@
 #ifndef __SYS_PROTO_IMX6_
 #define __SYS_PROTO_IMX6_
 
+#include <asm/gpio.h>
 #include <asm/mach-imx/sys_proto.h>
 #include <asm/arch/iomux.h>
 
@@ -18,7 +19,7 @@
 				   USBPHY_PWD_RXPWDRX))
 
 int imx6_pcie_toggle_power(void);
-int imx6_pcie_toggle_reset(void);
+int imx6_pcie_toggle_reset(struct gpio_desc *gpio, bool active_high);
 
 enum ldo_reg {
 	LDO_ARM,