cris/PCI: Remove unused pci_mem_start

Remove unused 'pci_mem_start' variable.
Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Mikael Starvik <starvik@axis.com>
CC: Jesper Nilsson <jesper.nilsson@axis.com>

arch/cris/include/asm/pci.h

@@ -11,7 +11,6 @@
 
 #define pcibios_assign_all_busses(void) 1
 
-extern unsigned long pci_mem_start;
 #define PCIBIOS_MIN_IO		0x1000
 #define PCIBIOS_MIN_MEM		0x10000000