perf trace scripting: remove system-wide param from shell scripts

Including -a unconditionally when recording doesn't allow for the
option of running scripts without it.  Future patches will add add it
back if needed at run-time.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Acked-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>