Add the pinctrl state name (default) for the UART/USART/LPUART
peripherals. Changes performed using the following Python script run
from the repository root:
```
from pathlib import Path
import re
for fpath in Path(".").glob("boards/arm/**/*.dts"):
lines = open(fpath).readlines()
is_stm32 = False
for line in lines:
if "stm32" in line:
is_stm32 = True
break
if not is_stm32:
continue
with open(fpath, "w") as f:
for line in lines:
f.write(line)
m = re.match(r"(\s+)pinctrl-0.*us?art.*", line)
if m:
f.write(m.group(1) + "pinctrl-names = \"default\";\n")
```
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
