arm: testsuite: avoid problems with -mfpu=auto in attr-crypto.c

This test overrides the architecture, but fails to describe which
floating-point features are needed.  This causes problems if the ABI
requires FP for parameter passing and -mfpu=auto is selected, so ensure
that one is specified.

gcc/testsuite:

	* gcc.target/arm/attr-crypto.c: Add +simd to the -march
	specification.

gcc/testsuite/gcc.target/arm/attr-crypto.c

@@ -3,7 +3,7 @@
    pragma.  */
 /* { dg-skip-if "-mpure-code supports M-profile only" { *-*-* } { "-mpure-code" } } */
 /* { dg-require-effective-target arm_fp_ok } */
-/* { dg-options "-O2 -march=armv8-a" } */
+/* { dg-options "-O2 -march=armv8-a+simd" } */
 /* { dg-add-options arm_fp } */
 
 /* Reset fpu to a value compatible with the next pragmas.  */