[PowerPC] stop folding if result rlwinm mask is wrap while original rlwinm is not.

%1:g8rc = RLWINM8 %0:g8rc, 0, 16, 9
%2:g8rc = RLWINM8 killed %1:g8rc, 0, 0, 31
->
%2:g8rc = RLWINM8 %0:g8rc, 0, 16, 9

The above folding is wrong. Before transformation, %2:g8rc is 32 bit value. After
transformation, %2:g8rc becomes a 64 bit value.
This patch fixes above issue.

Reviewed by: steven.zhang

Differential Revision: https://reviews.llvm.org/D71833