powerpc/44x: Declare primary_uic static in uic.c

powerpc/44x: Declare primary_uic static in uic.c

primary_uic is not used outside uic.c, declare it static.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411101746.lD8YdVzY-lkp@intel.com/
Fixes: e58923ed1437 ("[POWERPC] Add arch/powerpc driver for UIC, PPC4xx interrupt controller")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/0e11233d30333610ab460b3a1fd0f43c3a51e34d.1736331884.git.christophe.leroy@csgroup.eu