Resolve structural conflict between:

  59566b0b: ("x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up")

which introduced a new reference to 'ftrace_epilogue', and:

  0298739b: ("x86,ftrace: Fix ftrace_regs_caller() unwind")

Which renamed it to 'ftrace_caller_end'. Rename the new usage site in the merge commit.
Signed-off-by: Ingo Molnar <mingo@kernel.org>