i386: Use DEV_HYPERV to enable HyperV APIC vector

This avoids requiring both 'device hyperv' and 'options HYPERV' for
kernel configs.  Instead, just 'device hyperv' can now be used
matching the kernel configuration used for amd64.

Reviewed by:	imp
Differential Revision:	https://reviews.freebsd.org/D44783

sys/conf/options.i386

@@ -97,7 +97,7 @@ NPX_DEBUG		opt_npx.h
 BPF_JITTER		opt_bpf.h
 
 # Hyper-V support
-HYPERV			opt_hyperv.h
+DEV_HYPERV		opt_hyperv.h
 
 XENHVM			opt_global.h
 

sys/i386/conf/GENERIC

@@ -327,8 +327,6 @@ device		virtio_balloon		# VirtIO Memory Balloon device
 device		kvm_clock		# KVM paravirtual clock driver
 
 # HyperV drivers and enhancement support
-# NOTE: HYPERV depends on hyperv.  They must be added or removed together.
-options 	HYPERV			# Kernel support for HyperV drivers
 device		hyperv			# HyperV drivers
 
 # Xen HVM Guest Optimizations

sys/i386/conf/NOTES

@@ -660,7 +660,6 @@ device 		kvm_clock	# KVM paravirtual clock driver
 # Google Virtual NIC
 device		gve		# Google Virtual NIC (gVNIC) driver
 
-options 	HYPERV
 device		hyperv		# HyperV drivers
 device		hvhid		# HyperV HID device
 

sys/i386/i386/exception.S

@@ -450,7 +450,7 @@ ENTRY(fork_trampoline)
 #include <i386/i386/apic_vector.S>
 #endif
 
-#ifdef HYPERV
+#ifdef DEV_HYPERV
 	.data
 	.p2align 4
 	.text