ftrace/samples: Fix function size computation

In my_tramp1 function .size directive was placed above
ASM_RET instruction, leading to a wrong function size.

Link: https://lore.kernel.org/aK3d7vxNcO52kEmg@vova-pc


Fixes: 9d907f1a ("samples/ftrace: Fix asm function ELF annotations")
Signed-off-by: Vladimir Riabchun <ferr.lambarginio@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>