Rename lib_generic/ to lib/

Now that the other architecture-specific lib directories have been
moved out of the top-level directory there's not much reason to have the
'_generic' suffix on the common lib directory.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/board/purple/u-boot.lds b/board/purple/u-boot.lds
index 04a641a..236ece4 100644
--- a/board/purple/u-boot.lds
+++ b/board/purple/u-boot.lds
@@ -40,7 +40,7 @@
 	  common/main.o			(.text)
 	  common/dlmalloc.o		(.text)
 	  common/cmd_boot.o		(.text)
-	  lib_generic/zlib.o		(.text)
+	  lib/zlib.o		(.text)
 	  . = DEFINED(env_offset) ? env_offset : .;
 	  common/env_embedded.o	(.ppcenv)