hv: assign: change ptirq vpin source type from enum to macro

This patch fixes the MISRA-C violations on implicit type conversion.
For ptirq vpin source type, there is no need to define a enum.
Remove enum ptirq_vpin_source.
Define two macro:
- PTDEV_VPIN_IOAPIC
- PTDEV_VPIN_PIC

Tracked-On: #861
Signed-off-by: Binbin Wu <binbin.wu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/include/common/ptdev.h

@@ -14,10 +14,8 @@
 
 #define INVALID_PTDEV_ENTRY_ID 0xffffU
 
-enum ptirq_vpin_source {
-	PTDEV_VPIN_IOAPIC,
-	PTDEV_VPIN_PIC,
-};
+#define PTDEV_VPIN_IOAPIC	0x0U
+#define	PTDEV_VPIN_PIC		0x1U
 
 #define DEFINE_MSI_SID(name, a, b)	\
 union source_id (name) = {.msi_id = {.bdf = (a), .entry_nr = (b)} }