net/caif: Use pr_fmt

This patch standardizes caif message logging prefixes.

Add #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
Add missing "\n"s to some logging messages
Convert pr_warning to pr_warn

This changes the logging message prefix from CAIF: to caif:
for all uses but caif_socket.c and chnl_net.c.  Those now use
their filename without extension.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>