reset: allow building of reset simple driver if expert config selected

If CONFIG_EXPERT is selected, allow selection of CONFIG_RESET_SIMPLE
if needed by the user.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20220708165656.269507-1-ben.dooks@sifive.com