ppc4xx: Remove duplicated is_pci_host() functions

This patch introduces a weak default function for is_pci_host(),
returning 1. This is the default behaviour, since most boards only
implement PCI host functionality. This weak default can be overridden
by a board specific version if needed.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/prodrive/alpr/alpr.c b/board/prodrive/alpr/alpr.c
index 51335c4..e9e2bf3 100644
--- a/board/prodrive/alpr/alpr.c
+++ b/board/prodrive/alpr/alpr.c
@@ -218,7 +218,7 @@
 #endif /* defined(CONFIG_PCI) && defined(CONFIG_SYS_PCI_TARGET_INIT) */
 
 /*************************************************************************
- *  is_pci_host
+ * Override weak is_pci_host()
  *
  *	This routine is called to determine if a pci scan should be
  *	performed. With various hardware environments (especially cPCI and
diff --git a/board/prodrive/p3p440/p3p440.c b/board/prodrive/p3p440/p3p440.c
index 9a07852..e074007 100644
--- a/board/prodrive/p3p440/p3p440.c
+++ b/board/prodrive/p3p440/p3p440.c
@@ -235,7 +235,7 @@
 #endif				/* defined(CONFIG_PCI) && defined(CONFIG_SYS_PCI_TARGET_INIT) */
 
 /*************************************************************************
- *  is_pci_host
+ * Override weak is_pci_host()
  *
  *	This routine is called to determine if a pci scan should be
  *	performed. With various hardware environments (especially cPCI and