caif: Bugfix add check NULL pointer before calling functions.
caif: Bugfix add check NULL pointer before calling functions.

Add check on layer->dn != NULL before calling functions in
layer below.

Signed-off-by: Sjur Brændeland <90c9f68dc7b20ac89683f2c4f55e4a05e8dbf9ad@stericsson.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs