CleanSpec: Clean up $(PRODUCT_OUT)/recovery/root/sdcard.

Incremental build going across CL in [1] needs to remove the old
symlink to avoid hitting mkdir error.

[1]: commit 3f56a330412b56212acc5a9ed19b747c8943b7f2

Change-Id: Iff62ed55eb2782ba3e1e9b6de39a691de2427384
1 file changed