bus: ti-sysc: Fix cast to enum warning

Fix warning for "cast to smaller integer type 'enum sysc_soc' from 'const
void *'".

Cc: Nishanth Menon <nm@ti.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308150723.ziuGCdM3-lkp@intel.com/
Fixes: e1e1e9bb

 ("bus: ti-sysc: Fix build warning for 64-bit build")
Signed-off-by: Tony Lindgren <tony@atomide.com>