reset: qcom-aoss: Allow CONFIG_RESET_QCOM_AOSS to be a tristate

Allow CONFIG_RESET_QCOM_AOSS to be set as as =m to allow for the
driver to be loaded from a modules.

Also replaces the builtin_platform_driver() line with
module_platform_driver() and adds a MODULE_DEVICE_TABLE() entry.

Cc: Todd Kjos <tkjos@google.com>
Cc: Alistair Delva <adelva@google.com>
Cc: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>