powerpc/ftrace: Use FTRACE_REGS_ADDR to identify the correct ftrace trampoline

Instead of keying off DYNAMIC_FTRACE_WITH_REGS, use FTRACE_REGS_ADDR to
identify the proper ftrace trampoline address to use.
Signed-off-by: Naveen N Rao <naveen@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/6045a280a57a7ea937a5bb13ccac747026dbfb07.1687166935.git.naveen@kernel.org

arch/powerpc/kernel/trace/ftrace.c

@@ -745,14 +745,9 @@ int __init ftrace_dyn_arch_init(void)
 	};
 #endif
 
-	unsigned long addr;
+	unsigned long addr = FTRACE_REGS_ADDR;
 	long reladdr;
 
-	if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
-		addr = ppc_global_function_entry((void *)ftrace_regs_caller);
-	else
-		addr = ppc_global_function_entry((void *)ftrace_caller);
-
 	if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
 		for (i = 0; i < 2; i++) {
 			reladdr = addr - (unsigned long)tramp[i];