kernel/modules: fix crypto API RNG for >=4.2

kernel/modules: fix crypto API RNG for >=4.2

Since kernel 4.2, DRBG is the default crypto API RNG, replacing krng. As
DRBG is not enabled, there is no crypto API RNG available when running
kernel 4.2 or later. Because of this, IPsec SAs fail to install. In
strongSwan, this results in a vague error that is difficult to debug:

received netlink error: No such file or directory (2)

Solve this by adding DRBG to the kmod-crypto-rng package. As enabling
DRBG in the kernel config also enables the Jitterentropy RNG, include it
in kmod-crypto-rng instead of having it in a separate package.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@47827 3c298f89-4303-0410-b956-a3cf2f4a3e73