x86: Always inline task_size_max()

Fix:

vmlinux.o: warning: objtool: handle_bug()+0x10: call to task_size_max() leaves .noinstr.text section

When #UD isn't a BUG, we shouldn't violate noinstr (we'll still
probably die, but that's another story).

Fixes: 025768a966a3 ("x86/cpu: Use alternative to generate the TASK_SIZE_MAX constant")
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/x86/include/asm/page_64.h

···
  *
  * With page table isolation enabled, we map the LDT in ... [stay tuned]
  */
-static inline unsigned long task_size_max(void)
+static __always_inline unsigned long task_size_max(void)
 {
 	unsigned long ret;