powerpc: drop hard_reset_now() and poweroff_now() declaration

Those function have never existed. Drop their declaration.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/edcdd72a36495d25213c0256c8022367458e0d19.1596716418.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/processor.h

@@ -436,8 +436,6 @@ extern void power9_idle_type(unsigned long stop_psscr_val,
 			      unsigned long stop_psscr_mask);
 
 extern void flush_instruction_cache(void);
-extern void hard_reset_now(void);
-extern void poweroff_now(void);
 extern int fix_alignment(struct pt_regs *);
 extern void _nmask_and_or_msr(unsigned long nmask, unsigned long or_val);