build: Update x86_64 and uart_16550

These dependencies require update for updating Rust toolchain.

Signed-off-by: Akira Moroo <retrage01@gmail.com>

Author: retrage

Cargo.lock

@@ -26,10 +26,10 @@ coreboot = []
 
 [dependencies]
 bitflags = "1.2"
-x86_64 = "0.13.1"
+x86_64 = "0.13.2"
 atomic_refcell = "0.1"
 r-efi = "3.2.0"
-uart_16550 = "0.2.10"
+uart_16550 = "0.2.12"
 linked_list_allocator = "0.8.11"
 
 [dev-dependencies]