Add kernel network info description checks

To ensure that the description string in the network info response is
correctly null-terminated and that the string will fit into the UAPI
struct. The kernel will now check for the null-termination and verify
that the UAPI struct can hold the expected string size.

Change-Id: I8097a04c6ee4e80f1ab62a66e7323d2462c2c23a
Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>