aarch64: fix get time runtime service failure

When enable efi_rtc inside guest kernel, a warning occurs:

[    0.764401] [Firmware Bug]: Unable to handle paging request in EFI runtime service
[    0.770671] ------------[ cut here ]------------
[    0.772014] WARNING: CPU: 0 PID: 1 at drivers/firmware/efi/runtime-wrappers.c:262 virt_efi_get_time+0x12c/0x17c

It derives from that there is lack of memory map descriptor for IO address
of RTC_PL031 passed to kernel. Allocate IO Map for it before execute
kernel/bootloader can avoid this failure and then we can get the right
time inside guest.

Fixes: #289
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>

Author: jongwu

src/efi/mod.rs

@@ -994,6 +994,15 @@ fn populate_allocator(info: &dyn bootinfo::Info, image_address: u64, image_size:
         );
     }
 
+    // Add IO map for RTC PL031 on aarch64
+    #[cfg(target_arch = "aarch64")]
+    ALLOCATOR.borrow_mut().add_initial_allocation(
+        efi::MEMORY_MAPPED_IO,
+        1,
+        crate::arch::aarch64::layout::map::mmio::PL031_START as u64,
+        r_efi::efi::MEMORY_RUNTIME,
+    );
+
     // Add the loaded binary
     ALLOCATOR.borrow_mut().allocate_pages(
         efi::ALLOCATE_ADDRESS,