package/pkg-generic.mk: enable hash checks for svn tarbals

With commit 89f5e989 support for
reproducible archives was added. Thus archives generated from svn do no
longer needs to be added to BR_NO_CHECK_HASH_FOR.

Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>