style: edtlib: Remove the redundant call arguments

Remove the redundant positional argument in
open function to fix the Ruff UP015 warning.

Signed-off-by: James Roy <rruuaanng@outlook.com>

.ruff-excludes.toml

@@ -444,7 +444,6 @@
     "B904",     # https://docs.astral.sh/ruff/rules/raise-without-from-inside-except
     "SIM118",   # https://docs.astral.sh/ruff/rules/in-dict-keys
     "UP007",    # https://docs.astral.sh/ruff/rules/non-pep604-annotation
-    "UP015",    # https://docs.astral.sh/ruff/rules/redundant-open-modes
 ]
 "./scripts/dts/python-devicetree/src/devicetree/grutils.py" = [
     "E501",     # https://docs.astral.sh/ruff/rules/line-too-long

scripts/dts/python-devicetree/src/devicetree/edtlib.py

@@ -2457,7 +2457,7 @@ def load_vendor_prefixes_txt(vendor_prefixes: str) -> dict[str, str]:
     representation mapping a vendor prefix to the vendor name.
     """
     vnd2vendor: dict[str, str] = {}
-    with open(vendor_prefixes, 'r', encoding='utf-8') as f:
+    with open(vendor_prefixes, encoding='utf-8') as f:
         for line in f:
             line = line.strip()