hv: clean up udelay/mdelay related code

- replace the usage of mdelay with udelay
- remove lib/mdelay.c
- rename udelay.c to misc.c
  future other small APIs could put in misc.c

Tracked-On: #861
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/lib/misc.c

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2018 Intel Corporation. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <hv_lib.h>
+
+void udelay(uint32_t us)
+{
+	uint64_t dest_tsc, delta_tsc;
+
+	/* Calculate number of ticks to wait */
+	delta_tsc = us_to_ticks(us);
+	dest_tsc = rdtsc() + delta_tsc;
+
+	/* Loop until time expired */
+	while (rdtsc() < dest_tsc) {
+	}
+}