lib: dhry: add missing closing parenthesis

The help text for the Dhrystone benchmark test lacks a matching closing
parenthesis.

Link: https://lkml.kernel.org/r/772b43271bcb3dd17a6aae671b2084f08c05b079.1705934853.git.geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>