powerpc/ptrace: Refactor regs_set_return_{msr/ip}

regs_set_return_msr() and regs_set_return_ip() have a copy
of the code of set_return_regs_changed().

Call the later instead.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/baf64a91557d3811c155616a6aa23ed7b3b21da4.1624619582.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/ptrace.h

@@ -146,19 +146,13 @@ static inline void set_return_regs_changed(void)
 static inline void regs_set_return_ip(struct pt_regs *regs, unsigned long ip)
 {
 	regs->nip = ip;
-#ifdef CONFIG_PPC_BOOK3S_64
-	local_paca->hsrr_valid = 0;
-	local_paca->srr_valid = 0;
-#endif
+	set_return_regs_changed();
 }
 
 static inline void regs_set_return_msr(struct pt_regs *regs, unsigned long msr)
 {
 	regs->msr = msr;
-#ifdef CONFIG_PPC_BOOK3S_64
-	local_paca->hsrr_valid = 0;
-	local_paca->srr_valid = 0;
-#endif
+	set_return_regs_changed();
 }
 
 static inline void regs_add_return_ip(struct pt_regs *regs, long offset)