xtensa: ISS: add platform_pcibios_init

Provide pcibios initialization function in case PCI is enabled in the
kernel config. This allows building kernel in allmodconfig
configuration.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/platforms/iss/setup.c

@@ -38,6 +38,12 @@ void __init platform_init(bp_tag_t* bootparam)
 
 }
 
+#ifdef CONFIG_PCI
+void platform_pcibios_init(void)
+{
+}
+#endif
+
 void platform_halt(void)
 {
 	printk (" ** Called platform_halt(), looping forever! **\n");