m68k: math-emu: Fix incorrect file reference in fp_log.c

The file comment header refers to the wrong file.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/faf2244c3c80a4d70da5a18dd2a170a15b3ebd88.1692283195.git.geert@linux-m68k.org

arch/m68k/math-emu/fp_log.c

 /*
 
-  fp_trig.c: floating-point math routines for the Linux-m68k
+  fp_log.c: floating-point math routines for the Linux-m68k
   floating point emulator.
 
   Copyright (c) 1998-1999 David Huggins-Daines / Roman Zippel.