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/arch/x86/lapic.c

@@ -382,8 +382,10 @@ send_startup_ipi(enum intr_cpu_startup_shorthand cpu_startup_shorthand,
 	/* Give 10ms for INIT sequence to complete for old processors.
 	 * Modern processors (family == 6) don't need to wait here.
 	 */
-	if (boot_cpu_data.family != 6U)
-		mdelay(10U);
+	if (boot_cpu_data.family != 6U) {
+		/* delay 10ms */
+		udelay(10000U);
+	}
 
 	/* De-assert INIT IPI */
 	write_lapic_reg32(LAPIC_INT_COMMAND_REGISTER_1, icr.value_32.hi_32);