signal/x86: Inline fill_sigtrap_info in it's only caller send_sigtrap

The function fill_sigtrap_info now only has one caller so remove
it and put it's contents in it's caller.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>