MIPS32: Add missing swaps to codegen

Add swaps between fp registers and stack.
Also added emit_swap_mips_test.

Test: mma -j2 test-art-target-run-test on CI20
Test: mma test-art-host-gtest-emit_swap_mips_test

Change-Id: I38e7be6a86d9ad36a82e9d4293e9a6971b6e016a