testsuite: Skip intrinsics test if arm

In the test cases, it's clearly written that intrinsics is not
implemented on arm*. A simple xfail does not help since there are
link error and that would cause an UNRESOLVED testcase rather than
XFAIL.
By changing to dg-skip-if, the entire test case is omitted.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/advsimd-intrinsics/vld1x2.c: Replace
	dg-xfail-if with dg-skip-if.
	* gcc.target/aarch64/advsimd-intrinsics/vld1x3.c: Likewise.
	* gcc.target/aarch64/advsimd-intrinsics/vld1x4.c: Likewise.

Co-Authored-By: Yvan ROUX  <yvan.roux@foss.st.com>
Signed-off-by: Torbjörn SVENSSON  <torbjorn.svensson@foss.st.com>

gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vld1x2.c

@@ -1,6 +1,6 @@
 /* We haven't implemented these intrinsics for arm yet.  */
-/* { dg-xfail-if "" { arm*-*-* } } */
 /* { dg-do run } */
+/* { dg-skip-if "unsupported" { arm*-*-* } } */
 /* { dg-options "-O3" } */
 
 #include <arm_neon.h>

gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vld1x3.c

@@ -1,6 +1,6 @@
 /* We haven't implemented these intrinsics for arm yet.  */
-/* { dg-xfail-if "" { arm*-*-* } } */
 /* { dg-do run } */
+/* { dg-skip-if "unsupported" { arm*-*-* } } */
 /* { dg-options "-O3" } */
 
 #include <arm_neon.h>

gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vld1x4.c

@@ -1,6 +1,6 @@
 /* We haven't implemented these intrinsics for arm yet.  */
-/* { dg-xfail-if "" { arm*-*-* } } */
 /* { dg-do run } */
+/* { dg-skip-if "unsupported" { arm*-*-* } } */
 /* { dg-options "-O3" } */
 
 #include <arm_neon.h>