[arm] XFAIL advsimd-intrinsics/vld1x2.c

[arm] XFAIL advsimd-intrinsics/vld1x2.c

This recently added test fails on arm. We haven't implemented these intrinsics for arm
(any volunteers?) so for now let's XFAIL these on that target.
Also, the float64 versions of these intrinsics are not supposed to be available on arm
so this patch slightly adjusts the test to not include them for aarch32.
In any case the entire test is XFAILed on arm, so this doesn't have any noticeable
effect.

The same number of tests (PASS) still occur on aarch64 but now they appear as XFAIL
rather than FAIL on arm.

    * gcc.target/aarch64/advsimd-intrinsics/vld1x2.c: Make float64
    tests specific to aarch64.  XFAIL test on arm.

From-SVN: r257090