powerpc/4xx: Add missing includes to fix no previous prototype errors

A W=1 build of ppc40x_defconfig throws the followings errors:

CC arch/powerpc/platforms/4xx/uic.o
arch/powerpc/platforms/4xx/uic.c:274:13: warning: no previous prototype for 'uic_init_tree' [-Wmissing-prototypes]
274 | void __init uic_init_tree(void)
| ^~~~~~~~~~~~~
arch/powerpc/platforms/4xx/uic.c:319:14: warning: no previous prototype for 'uic_get_irq' [-Wmissing-prototypes]
319 | unsigned int uic_get_irq(void)
| ^~~~~~~~~~~
CC arch/powerpc/platforms/4xx/machine_check.o
CC arch/powerpc/platforms/4xx/soc.o
arch/powerpc/platforms/4xx/soc.c:193:6: warning: no previous prototype for 'ppc4xx_reset_system' [-Wmissing-prototypes]
193 | void ppc4xx_reset_system(char *cmd)
| ^~~~~~~~~~~~~~~~~~~

Add missing includes to get the missing prototypes.

Signed-off-by: Christophe Leroy <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://msgid.link/c8253017[e-mail]

arch/powerpc/platforms/4xx/soc.c

···
 #include <asm/dcr.h>
 #include <asm/dcr-regs.h>
 #include <asm/reg.h>
+#include <asm/ppc4xx.h>
 
 static u32 dcrbase_l2c;
 

arch/powerpc/platforms/4xx/uic.c

···
 #include <asm/irq.h>
 #include <asm/io.h>
 #include <asm/dcr.h>
+#include <asm/uic.h>
 
 #define NR_UIC_INTS	32