firmware: imx: scu-pd: add specifying the base of domain name index support

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>