change ktap_vaule n field to "long" instead of "int"

In x86-64 Linux, int is just 4 bytes, which cannot respesent
ip vaule(8 bytes).

we also can use "void *" to respesent ip, but then we need
to use a new type like TYPE_IP, currently we don't use that
method.

This patch also add some kmalloc failure return check.

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@gmail.com>
disable ftrace:function when tracing "*:*"

If we enable ftrace:function when all tracepoints enabled,
then there will have all function events which flushed others
tracepoints, because function event will be the most event.

Check the effect of this change on scripts/tracepoints_histogram.kp

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@gmail.com>