pshufd requires 16 byte aligned memory or a register.
Use movd to a register to avoid a segfault if memory for float
is misaligned

Bug: libyuv:759
Test: 32 bit build of LibYUVPlanarTest.TestHalfFloatPlane_16bit_denormal
Change-Id: I6fdcc4317453af5acd4700f9d46425bb2f4a205b
Reviewed-on: https://chromium-review.googlesource.com/840459Reviewed-by: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
Commit-Queue: Frank Barchard <fbarchard@chromium.org>