pci: pcie_dw_rockchip: Fixed the below compilation error

Use the generic error number instead of specific error number.
Changes fix the below error.

drivers/pci/pcie_dw_rockchip.c: In function 'rk_pcie_read':
drivers/pci/pcie_dw_rockchip.c:70:10: error: 'PCIBIOS_UNSUPPORTED'
                        undeclared (first use in this function)
   70 |   return PCIBIOS_UNSUPPORTED;
      |          ^~~~~~~~~~~~~~~~~~~
drivers/pci/pcie_dw_rockchip.c: In function 'rk_pcie_write':
drivers/pci/pcie_dw_rockchip.c:90:10: error: 'PCIBIOS_UNSUPPORTED'
                        undeclared (first use in this function)
   90 |   return PCIBIOS_UNSUPPORTED;
      |          ^~~~~~~~~~~~~~~~~~~

Cc: Patrick Wildt <patrick@blueri.se>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Patrick Wildt <patrick@blueri.se>
Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/pci/pcie_dw_rockchip.c b/drivers/pci/pcie_dw_rockchip.c
index bc22af4..3ac2434 100644
--- a/drivers/pci/pcie_dw_rockchip.c
+++ b/drivers/pci/pcie_dw_rockchip.c
@@ -67,7 +67,7 @@
 {
 	if ((uintptr_t)addr & (size - 1)) {
 		*val = 0;
-		return PCIBIOS_UNSUPPORTED;
+		return -EOPNOTSUPP;
 	}
 
 	if (size == 4) {
@@ -87,7 +87,7 @@
 static int rk_pcie_write(void __iomem *addr, int size, u32 val)
 {
 	if ((uintptr_t)addr & (size - 1))
-		return PCIBIOS_UNSUPPORTED;
+		return -EOPNOTSUPP;
 
 	if (size == 4)
 		writel(val, addr);