sh: fcnvds fix with denormalized numbers on SH-4 FPU.

This fixes a bug in the FPU exception handler for the FCNVDS instruction.
To get the register number the instruction is shifted right by 9,
though it should be shifted right by 8.

More information at ST Linux bugzilla:

	https://bugzilla.stlinux.com/show_bug.cgi?id=4892

Signed-off-by: Giuseppe Di Giore <giuseppe.di-giore@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>