sh: dwarf: Make dwarf_lookup_fde() static

arch/sh/kernel/dwarf.c:347:19: warning: no previous prototype for 'dwarf_lookup_fde' [-Wmissing-prototypes]

There are no users outside this file, so make it static.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/55e8261a354e8ec4d375754e404c6c1d303af715.1709326528.git.geert+renesas@glider.beSigned-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

arch/sh/kernel/dwarf.c

@@ -344,7 +344,7 @@ static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
  *	dwarf_lookup_fde - locate the FDE that covers pc
  *	@pc: the program counter
  */
-struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
+static struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
 {
 	struct rb_node **rb_node = &fde_root.rb_node;
 	struct dwarf_fde *fde = NULL;