The rlwinm specification includes the ROTL32 operation, which is defined
to be a left rotation of two copies of the least significant 32 bits of
the source GPR.

The current implementation is incorrect on 64-bit implementations in that
it rotates a single copy of the least significant 32 bits, padding with
zeroes in the most significant bits.

Fix the code to properly implement this ROTL32 operation.

Example:
R3 = F7487D82EC6F75DF
rlwinm 3,3,5,12,4

R3 expected : 8DEEBBFD880EBBFD
R3 actual   : 00000000880EBBFD (without this fix)

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