As the domain resource id in the same type may not be continuous, so it's
hard to describe all such power domains with current struct imx_sc_pd_range.

Adding the optional base for domain name index to address this issue.
Then we can add the discrete domains easily later.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>