scripts/tags.sh: Include trace_*_rcuidle() in tags

Every tracepoint creates two functions, the usual one 'trace_*()'
and the rcuidle one 'trace_*_rcuidle()'. Add regex for the
rcuidle variant so that we can jump to the tracepoints that use
rcuidle.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michal Marek <mmarek@suse.com>