powerpc: 85xx: mark local functions static

These functions are either used in only one file and can just be
made static or need an #include statement to avoid a warning:

arch/powerpc/platforms/85xx/mpc8536_ds.c:30:13: error: no previous prototype for 'mpc8536_ds_pic_init' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1010rdb.c:27:13: error: no previous prototype for 'p1010_rdb_pic_init' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1022_ds.c:373:6: error: no previous prototype for 'p1022ds_set_pixel_clock' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1022_ds.c:422:1: error: no previous prototype for 'p1022ds_valid_monitor_port' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1022_ds.c:435:13: error: no previous prototype for 'p1022_ds_pic_init' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1022_rdk.c:43:6: error: no previous prototype for 'p1022rdk_set_pixel_clock' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1022_rdk.c:92:1: error: no previous prototype for 'p1022rdk_valid_monitor_port' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/p1022_rdk.c:99:13: error: no previous prototype for 'p1022_rdk_pic_init' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/socrates_fpga_pic.c:273:13: error: no previous prototype for 'socrates_fpga_pic_init' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/xes_mpc85xx.c:40:13: error: no previous prototype for 'xes_mpc85xx_pic_init' [-Werror=missing-prototypes]
arch/powerpc/platforms/85xx/mvme2500.c:24:13: error: no previous prototype for 'mvme2500_pic_init' [-Werror=missing-prototypes]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240123125148.2004648-2-arnd@kernel.org