target-ppc: Bug Fix: rlwimi

target-ppc: Bug Fix: rlwimi

The rlwimi 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.

Also fix the special case of MB=31 and ME=0 to copy the entire contents
of the source GPR.

Examples:

R3 FFFFFFFFFFFFFFF0
rlwimi 3,3,29,14,1
R3 expected : 1FFFFFFE3FFFFFFE
R3 actual   : 000000003FFFFFFE (without this patch)

R3 ED7EB4DD824F0853
rlwimi 3,3,10,31,0
R3 expected : 3C214E09024F0853
R3 actual   : 00000000024F0853 (without this patch)

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