perf tools: Remove unnecessary parentheses

The hashmap API used to require parentheses for the hashmap argument if
it's not a pointer type.  It's now fixed so let's drop the parentheses.

Link: https://lore.kernel.org/r/20241009202009.884884-2-namhyung@kernel.org


Signed-off-by: Namhyung Kim <namhyung@kernel.org>