Switch to arm_fp_dp_ok effective-target in tests that require
double-precision support from the FPU.

2020-03-24  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/testsuite/
	* gcc/arm/vfp-1.c: Use arm_fp__ok effective-target.
	* gcc.target/arm/vfp-ldmdbd.c: Likewise.
	* gcc.target/arm/vfp-ldmiad.c: Likewise.
	* gcc.target/arm/vfp-stmdbd.c: Likewise.
	* gcc.target/arm/vfp-stmiad.c: Likewise.
	* gcc.target/arm/vnmul-1.c: Likewise.
	* gcc.target/arm/vnmul-3.c: Likewise.
	* gcc.target/arm/vnmul-4.c: Likewise.