[AArch64] Fix big-endian testisms introduced by NEON gimple lowering patch

[AArch64] Fix big-endian testisms introduced by NEON gimple lowering patch

This patch reverts the tests for big-endian after the NEON gimple lowering
patch.  The earlier patch only lowers NEON loads and stores for little-endian,
meaning the codegen now differs between endinanness so we need target specific
testing.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/fmla_intrinsic_1.c: Fix big-endian testism.
	* gcc.target/aarch64/fmls_intrinsic_1.c: Likewise.
	* gcc.target/aarch64/fmul_intrinsic_1.c: Likewise.