[XTENSA] Move string-io functions to io.c from pci.c

The string-io functions (outs{bwl}, ins{bwl}) are independent from
the PCI option and should be in a separate file.

Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/kernel/Makefile b/arch/xtensa/kernel/Makefile
index 0e3ac68..f582d6a 100644
--- a/arch/xtensa/kernel/Makefile
+++ b/arch/xtensa/kernel/Makefile
@@ -7,7 +7,7 @@
 
 obj-y := align.o entry.o irq.o coprocessor.o process.o ptrace.o semaphore.o  \
 	 setup.o signal.o syscall.o time.o traps.o vectors.o platform.o  \
-	 pci-dma.o init_task.o
+	 pci-dma.o init_task.o io.o
 
 ## windowspill.o