soc: ti: ti_sci_pm_domains: Populate name for genpd

Commit b6a1d093 ("PM / Domains: Extend generic power domain
debugfs") now creates a debugfs directory for each genpd based on the
name of the genpd. Currently no name is given to the genpd created by
ti_sci_pm_domains driver so because of this we see a NULL pointer
dereferences when it is accessed on boot when the debugfs entry creation
is attempted.

Give the genpd a name before registering it to avoid this.

Fixes: 52835d59 ("soc: ti: Add ti_sci_pm_domains driver")
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>