HV:refine 'apic_page' & 'pir_desc' in 'struct acrn_vlapic'

- update 'apic_page' field in 'struct acrn_vlapic',
   from pointer type to 'struct lapic_regs' type.

 - delete 'pir' and update 'pir_desc' to 'vlapic_pir_desc'
   type.

 - fix potential memory leak in 'vlapic_create()'
   should free allocated memory in case of registering
   mmio handler failure.

Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>

hypervisor/lib/memory.c

@@ -233,6 +233,10 @@ static void deallocate_mem(struct mem_pool *pool, void *ptr)
 	}
 }
 
+/*
+ * The return address will be CPU_PAGE_SIZE aligned if 'num_bytes' is greater
+ * than CPU_PAGE_SIZE.
+ */
 void *malloc(unsigned int num_bytes)
 {
 	void *memory = NULL;