python-packages: Clean up Makefiles

This removes:

* Python 3 variants (VARIANT:=python3)

* "for Python3" from package titles

* Package selection condition from package dependencies, e.g.
  +PACKAGE_python3-six:python3-light replaced with +python3-light

* "Default" package information sections, e.g.
  Package/python-six/Default removed and package details merged into
  Package/python3-six

* "(Variant for Python3)" from package descriptions

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

lang/python/python-pyserial/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=python-pyserial
 PKG_VERSION:=3.4
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PYPI_NAME:=pyserial
 PKG_HASH:=6e2d401fdee0eab996cf734e67773a0143b932772ca8b42451440cfed942c627
@@ -21,18 +21,13 @@ include ../pypi.mk
 include $(INCLUDE_DIR)/package.mk
 include ../python3-package.mk
 
-define Package/python-pyserial/Default
+define Package/python3-pyserial
   SECTION:=lang-python
   CATEGORY:=Languages
   SUBMENU:=Python
-  URL:=https://github.com/pyserial/pyserial
-endef
-
-define Package/python3-pyserial
-$(call Package/python-pyserial/Default)
   TITLE:=python3-pyserial
-  DEPENDS:=+PACKAGE_python3-pyserial:python3-light
-  VARIANT:=python3
+  URL:=https://github.com/pyserial/pyserial
+  DEPENDS:=+python3-light
 endef
 
 define Package/python3-pyserial/description
@@ -40,8 +35,6 @@ This module encapsulates the access for the serial port. It provides backends
 for Python running on Windows, OSX, Linux, BSD (possibly any POSIX compliant
 system) and IronPython. The module named "serial" automatically selects the
 appropriate backend.
-.
-(Variant for Python3)
 endef
 
 $(eval $(call Py3Package,python3-pyserial))