msm: remote_spinlock: Stub out swp type on THUMB2 kernels

There is no support for the swp instruction in the THUMB2
instruction set, so just remove the code in this case. Nobody
should be using the swp type of remote spinlock on THUMB2 kernels
anyway.

Change-Id: Id3fcf9e08cd24bb6e015b821cffc474c2e6461f7
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>