[POWERPC] Add bootwrapper function to get virtual reg from the device tree.

This patch adds a new generic device tree processing function that retrieves
virtual reg addresses from the device tree to the bootwrapper code. It also
updates the bootwrapper code to use the new function.

dt_get_virtual_reg() retrieves the virtual reg addresses from the
"virtual-reg" property. If the property can't be found, it uses the "reg"
property and walks the tree to translate it to absolute addresses.

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/boot/ops.h b/arch/powerpc/boot/ops.h
index 4b0544b..321e2f5 100644
--- a/arch/powerpc/boot/ops.h
+++ b/arch/powerpc/boot/ops.h
@@ -95,6 +95,7 @@
 int dt_xlate_addr(void *node, u32 *buf, int buflen, unsigned long *xlated_addr);
 int dt_is_compatible(void *node, const char *compat);
 void dt_get_reg_format(void *node, u32 *naddr, u32 *nsize);
+int dt_get_virtual_reg(void *node, void **addr, int nres);
 
 static inline void *finddevice(const char *name)
 {