target-arm: Set softfloat cumulative exc flags from correct FPSCR bits

target-arm: Set softfloat cumulative exc flags from correct FPSCR bits

When handling a write to the ARM FPSCR, set the softfloat cumulative
exception flags from the cumulative flags in the FPSCR, not the
exception-enable bits. Also don't apply a mask: vfp_exceptbits_to_host
will only look at the correct bits anyway.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>