Bluetooth: Mesh: Fix friendship counter increasing order

For Bluetooth Mesh, counter shall be increasing by one when
every try to establishing friendship.

Counter to be used when create friendship security material.
So this value shall be consist between friend and lpn.

Due to zephyr bluetooth mesh send previous counter, after that
it will automatically increase one, which will result in the
incorrect generation of friend key when key rephase.

Signed-off-by: Lingao Meng <menglingao@xiaomi.com>