Trap SVE instructions until we have SVE support

When running on hardware that supports SVE send the correct signal when
an SVE instruction is run.

Sponsored by:	The FreeBSD Foundation

sys/arm64/arm64/trap.c

@@ -593,6 +593,11 @@ do_el0_sync(struct thread *td, struct trapframe *frame)
 		panic("VFP exception in userland");
 #endif
 		break;
+	case EXCP_SVE:
+		call_trapsignal(td, SIGILL, ILL_ILLTRP, (void *)frame->tf_elr,
+		    exception);
+		userret(td, frame);
+		break;
 	case EXCP_SVC32:
 	case EXCP_SVC64:
 		svc_handler(td, frame);

sys/arm64/include/armreg.h

@@ -387,6 +387,7 @@
 #define	 EXCP_SVC64		0x15	/* SVC trap for AArch64 */
 #define	 EXCP_HVC		0x16	/* HVC trap */
 #define	 EXCP_MSR		0x18	/* MSR/MRS trap */
+#define	 EXCP_SVE		0x19	/* SVE trap */
 #define	 EXCP_FPAC		0x1c	/* Faulting PAC trap */
 #define	 EXCP_INSN_ABORT_L	0x20	/* Instruction abort, from lower EL */
 #define	 EXCP_INSN_ABORT	0x21	/* Instruction abort, from same EL */