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-pyopenssl_24.0.0.bb

@@ -3,7 +3,7 @@ HOMEPAGE = "https://pyopenssl.org/"
 LICENSE = "Apache-2.0"
 LIC_FILES_CHKSUM = "file://LICENSE;md5=3b83ef96387f14655fc854ddc3c6bd57"
 
-DEPENDS += "openssl ${PYTHON_PN}-cryptography"
+DEPENDS += "openssl python3-cryptography"
 
 SRC_URI[sha256sum] = "6aa33039a93fffa4563e655b61d11364d01264be8ccb49906101e02a334530bf"
 
@@ -14,9 +14,9 @@ PACKAGES =+ "${PN}-tests"
 FILES:${PN}-tests = "${libdir}/${PYTHON_DIR}/site-packages/OpenSSL/test"
 
 RDEPENDS:${PN}:class-target = " \
-    ${PYTHON_PN}-cryptography \
-    ${PYTHON_PN}-six \
-    ${PYTHON_PN}-threading \
+    python3-cryptography \
+    python3-six \
+    python3-threading \
 "
 RDEPENDS:${PN}-tests = "${PN}"