sh: math-emu: Add missing #include <asm/fpu.h>

arch/sh/math-emu/math.c:492:5: warning: no previous prototype for 'do_fpu_inst' [-Wmissing-prototypes]

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/cfda1ba2eadb75e2793e67d43df42fe4c04e4fcf.1709326528.git.geert+renesas@glider.be


Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>