The rlwnm 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 = 0000000000000002
R4 = 7FFFFFFFFFFFFFFF
rlwnm 3,3,4,31,16
R3 expected : 0000000100000001
R3 actual   : 0000000000000001 (without this patch)

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