python: Drop ${PYTHON_PN}

python 2 is gone and we don't need the abstraction now, drop the remaining usage
of this variable.

The definition in python3-dir.bbclass is left for now for other layers.

(From OE-Core rev: b566b1e32c7993d1ab7795562f648e52ce186a70)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python3-babel_2.14.0.bb

@@ -12,15 +12,15 @@ inherit pypi setuptools3
 CLEANBROKEN = "1"
 
 RDEPENDS:${PN} += " \
-    ${PYTHON_PN}-codecs \
-    ${PYTHON_PN}-difflib \
-    ${PYTHON_PN}-netserver \
-    ${PYTHON_PN}-numbers \
-    ${PYTHON_PN}-pickle \
-    ${PYTHON_PN}-pytz \
-    ${PYTHON_PN}-setuptools \
-    ${PYTHON_PN}-shell \
-    ${PYTHON_PN}-threading \
+    python3-codecs \
+    python3-difflib \
+    python3-netserver \
+    python3-numbers \
+    python3-pickle \
+    python3-pytz \
+    python3-setuptools \
+    python3-shell \
+    python3-threading \
 "
 
 BBCLASSEXTEND = "native nativesdk"