ANDROID: fs: Export d_absolute_path

The 0-day build bot reports the following build error, seen if SDCARD_FS
is built as module.

ERROR: "d_absolute_path" undefined!

Fixes: 84a1b7d3d312 ("Included sdcardfs source code for kernel 3.0")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
diff --git a/fs/dcache.c b/fs/dcache.c
index 5c7cc95..972741b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3184,6 +3184,7 @@
 		return ERR_PTR(error);
 	return res;
 }
+EXPORT_SYMBOL(d_absolute_path);
 
 /*
  * same as __d_path but appends "(deleted)" for unlinked files.