Add 0x prefix onto defmt'd pointers.

[jonathanpallant]

#![no_main]
#![no_std]

use test_pointers as _;

static MY_VALUE: [u8; 64] = [0xCC; 64];

#[cortex_m_rt::entry]
fn main() -> ! {
    let p = MY_VALUE.as_ptr();
    defmt::println!("Hello, world!, p1 = {:?}", p);
    test_pointers::exit()
}

(HOST) INFO  flashing program (2 pages / 8.00 KiB)
(HOST) INFO  success!
────────────────────────────────────────────────────────────────────────────────
Hello, world!, p1 = 0x15a2
└─ hello::__cortex_m_rt_main @ src/bin/hello.rs:12
────────────────────────────────────────────────────────────────────────────────
stack backtrace:
   0: lib::inline::__bkpt
        at ./asm/inline.rs:14:5
   1: __bkpt
        at ./asm/lib.rs:51:17
   2: test_pointers::exit
        at src/lib.rs:20:5
   3: hello::__cortex_m_rt_main
        at src/bin/hello.rs:14:5
   4: main
        at src/bin/hello.rs:8:1
   5: Reset
(HOST) WARN  call stack was corrupted; unwinding could not be completed
(HOST) INFO  device halted without error

Fixes #603

[Urhengulas]

bors r+

[bors]

Build succeeded:

• ci