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>

board/sc3/u-boot.lds

@@ -69,9 +69,9 @@ SECTIONS
     cpu/ppc4xx/cpu_init.o	(.text)
     cpu/ppc4xx/speed.o	(.text)
     common/dlmalloc.o	(.text)
-    lib_generic/crc32.o		(.text)
+    lib/crc32.o		(.text)
     arch/ppc/lib/extable.o	(.text)
-    lib_generic/zlib.o		(.text)
+    lib/zlib.o		(.text)
 
 /*    . = env_offset;*/
 /*    common/env_embedded.o(.text)*/