powerpc/time: Fix build failure due to do_hard_irq_enable() on PPC32

	  CC      arch/powerpc/kernel/time.o
	In file included from <command-line>:
	./arch/powerpc/include/asm/hw_irq.h: In function 'do_hard_irq_enable':
	././include/linux/compiler_types.h:335:45: error: call to '__compiletime_assert_35' declared with attribute error: BUILD_BUG failed
	  335 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
	      |                                             ^
	././include/linux/compiler_types.h:316:25: note: in definition of macro '__compiletime_assert'
	  316 |                         prefix ## suffix();                             \
	      |                         ^~~~~~
	././include/linux/compiler_types.h:335:9: note: in expansion of macro '_compiletime_assert'
	  335 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
	      |         ^~~~~~~~~~~~~~~~~~~
	./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
	   39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
	      |                                     ^~~~~~~~~~~~~~~~~~
	./include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG'
	   59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
	      |                     ^~~~~~~~~~~~~~~~
	./arch/powerpc/include/asm/hw_irq.h:483:9: note: in expansion of macro 'BUILD_BUG'
	  483 |         BUILD_BUG();
	      |         ^~~~~~~~~

should_hard_irq_enable() returns false on PPC32 so this BUILD_BUG() shouldn't trigger.

Force inlining of should_hard_irq_enable()

Fixes: 0faf20a1 ("powerpc/64s/interrupt: Don't enable MSR[EE] in irq handlers unless perf is in use")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/247e01e0e10f4dbc59b5ff89e81702eb1ee7641e.1641828571.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/hw_irq.h

@@ -473,7 +473,7 @@ static inline bool arch_irq_disabled_regs(struct pt_regs *regs)
 	return !(regs->msr & MSR_EE);
 }
 
-static inline bool should_hard_irq_enable(void)
+static __always_inline bool should_hard_irq_enable(void)
 {
 	return false;
 }