kernel/panic.c: do not append newline to the stack protector panic string

... because panic() itself already does this. Otherwise you have
line-broken trailer:

  [    1.836965] ---[ end Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: pgd_alloc+0x29e/0x2a0
  [    1.836965]  ]---

Link: http://lkml.kernel.org/r/20181008202901.7894-1-bp@alien8.de


Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>