[PATCH -next] parisc: stacktrace: add <linux/kernel.h> to prevent build error

[Randy Dunlap <rdunlap@xxxxxxxxxxxxx>]

stacktrace.c uses __kernel_text_address() so it needs to
include <linux/kernel.h>.  Otherwise there is a build error:

arch/parisc/kernel/stacktrace.c: In function 'walk_stackframe':
arch/parisc/kernel/stacktrace.c:25:21: error: implicit declaration of
function '__kernel_text_address'
[-Werror=implicit-function-declaration]
   25 |                 if (__kernel_text_address(info.ip))

Fixes: aeb1e833a4c3 ("parisc: Switch to ARCH_STACKWALK implementation")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
Cc: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: linux-parisc@xxxxxxxxxxxxxxx
---
 arch/parisc/kernel/stacktrace.c |    1 +
 1 file changed, 1 insertion(+)

--- linux-next-20211109.orig/arch/parisc/kernel/stacktrace.c
+++ linux-next-20211109/arch/parisc/kernel/stacktrace.c
@@ -8,6 +8,7 @@
  *
  *  TODO: Userspace stacktrace (CONFIG_USER_STACKTRACE_SUPPORT)
  */
+#include <linux/kernel.h>
 #include <linux/stacktrace.h>
 
 #include <asm/unwind.h>