h8300: fix PREEMPTION build, TI_PRE_COUNT undefined

Fix a build error for undefined 'TI_PRE_COUNT' by adding it to
asm-offsets.c.

  h8300-linux-ld: arch/h8300/kernel/entry.o: in function `resume_kernel': (.text+0x29a): undefined reference to `TI_PRE_COUNT'

Link: https://lkml.kernel.org/r/20210212021650.22740-1-rdunlap@infradead.org
Fixes: df2078b8 ("h8300: Low level entry")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/h8300/kernel/asm-offsets.c

@@ -63,6 +63,9 @@ int main(void)
 	OFFSET(TI_FLAGS, thread_info, flags);
 	OFFSET(TI_CPU, thread_info, cpu);
 	OFFSET(TI_PRE, thread_info, preempt_count);
+#ifdef CONFIG_PREEMPTION
+	DEFINE(TI_PRE_COUNT, offsetof(struct thread_info, preempt_count));
+#endif
 
 	return 0;
 }