hv: Fix identifier reuse

Now we have name reuse definitions in hypervisor as following:
"enum cpu_state cpu_state" in per_cpu.h,
"struct shell_cmd *shell_cmd" in shell_priv.h.
MISRAC requires that tag names shall not be reused anywhere
with in a program.So these definitions violate MISRAC rules
"identifier resue".This patch is used to fix it.

1. modify the definitions to "enum pcpu_boot_state boot_state"
and "struct shell_cmd *cmds".
2. modifty the relevant usage.

v1->v2
    update commit message to be more explicit.

v2->v3
    update the enum definition.

Tracked-On: #861
Signed-off-by: Junjun Shan <junjun.shan@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/include/arch/x86/cpu.h

@@ -268,12 +268,12 @@ extern spinlock_t trampoline_spinlock;
 #define BROADCAST_CPU_ID 0xfffeU
 
 /* CPU states defined */
-enum cpu_state {
-	CPU_STATE_RESET = 0,
-	CPU_STATE_INITIALIZING,
-	CPU_STATE_RUNNING,
-	CPU_STATE_HALTED,
-	CPU_STATE_DEAD,
+enum pcpu_boot_state {
+	PCPU_STATE_RESET = 0,
+	PCPU_STATE_INITIALIZING,
+	PCPU_STATE_RUNNING,
+	PCPU_STATE_HALTED,
+	PCPU_STATE_DEAD,
 };
 
 struct cpu_state_info {