scripts/feeds: Delete package/feeds folder in the clean procedure to prevent dangling links.

Hello,

if you run:
./scripts/feeds clean
It removes ./feeds folder but not ./package/feeds/ which is full of dangling links then. This patch fixes it.

Best Regards,
Martin Strbačka

Signed-off-by: Martin Strbacka <martin.strbacka@nic.cz>

SVN-Revision: 45738