package/python-matplotlib: drop redundant !PYTHON dependency

Having both:

       depends on !BR2_PACKAGE_PYTHON
       depends on BR2_PACKAGE_PYTHON3

is kind of useless, and we don't do that for any other Python package
that needs Python 3. So, this commit just drops the depends on
!BR2_PACKAGE_PYTHON.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/python-matplotlib/Config.in

@@ -1,6 +1,5 @@
 config BR2_PACKAGE_PYTHON_MATPLOTLIB
 	bool "python-matplotlib"
-	depends on !BR2_PACKAGE_PYTHON
 	depends on BR2_PACKAGE_PYTHON3
 	depends on BR2_PACKAGE_PYTHON_NUMPY_ARCH_SUPPORTS
 	select BR2_PACKAGE_FREETYPE # runtime