powerpc/kexec: Declare kexec_paca static

kexec_paca is exclusively used in kexec/core_64.c

Declare it static.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/094983ee851644165b7700c73cac63cfe20596cd.1646413435.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/asm-prototypes.h

@@ -24,9 +24,7 @@ extern struct task_struct *secondary_current;
 void start_secondary(void *unused);
 
 /* kexec */
-struct paca_struct;
 struct kimage;
-extern struct paca_struct kexec_paca;
 void kexec_copy_flush(struct kimage *image);
 
 /* pseries hcall tracing */

arch/powerpc/kexec/core_64.c

@@ -291,7 +291,7 @@ static union thread_union kexec_stack __init_task_data =
  * For similar reasons to the stack above, the kexecing CPU needs to be on a
  * static PACA; we switch to kexec_paca.
  */
-struct paca_struct kexec_paca;
+static struct paca_struct kexec_paca;
 
 /* Our assembly helper, in misc_64.S */
 extern void kexec_sequence(void *newstack, unsigned long start,