target/hppa: Copy instruction code into fr1 on FPU assist fault

target/hppa: Copy instruction code into fr1 on FPU assist fault

The hardware stores the instruction code in the lower bits of the FP
exception register #1 on FP assist traps.
This fixes the FP exception handler on Linux, as the Linux kernel uses
the value to decide on the correct signal which should be pushed into
userspace (see decode_fpu() in Linux kernel).

Signed-off-by: Helge Deller <deller@gmx.de>
(cherry picked from commit 923976dfe367b0bfed45ff660c369f3fe65604a7)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>