target-ppc: Bug Fix: srad

Fix the check for carry in the srad helper to properly construct
the mask -- a "1ULL" must be used (instead of "1") in order to
get the desired result.

Example:

R3 8000000000000000
R4 F3511AD4A2CD4C38
srad 3,3,4

Should *not* set XER[CA] but does without this patch.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
