hv: remove de-privilege boot mode support and remove vboot wrappers

Now ACRN supports direct boot mode, which could be SBL/ABL, or GRUB boot.
Thus the vboot wrapper layer can be removed and the direct boot functions
don't need to be wrapped in direct_boot.c:

- remove call to init_vboot(), and call e820_alloc_memory() directly at the
  time when the trampoline buffer is actually needed.
- Similarly, call CPU_IRQ_ENABLE() instead of the wrapper init_vboot_irq().
- remove get_ap_trampoline_buf(), since the existing function
  get_trampoline_start16_paddr() returns the exact same value.
- merge init_general_vm_boot_info() into init_vm_boot_info().
- remove vm_sw_loader pointer, and call direct_boot_sw_loader() directly.
- move get_rsdp_ptr() from vboot_wrapper.c to multiboot.c, and remove the
  wrapper over two boot modes.

Tracked-On: #5197
Signed-off-by: Zide Chen <zide.chen@intel.com>

hypervisor/common/vm_load.c

@@ -181,7 +181,7 @@ static void prepare_loading_rawimage(struct acrn_vm *vm)
 /**
  * @pre vm != NULL
  */
-int32_t direct_boot_sw_loader(struct acrn_vm *vm)
+int32_t vm_sw_loader(struct acrn_vm *vm)
 {
 	int32_t ret = 0;
 	struct sw_kernel_info *sw_kernel = &(vm->sw.kernel_info);