python-spidev: bump to version 3.1

Also add hash file.

And fixes:
http://autobuild.buildroot.net/results/abc/abca38e3e93b609c1040c1152de7cd59940e2c88/
It was using an absolute include_dirs in setup.py pointing to the host
kernel sources (/usr/src/linux). It didn't affect "normal" distros since
they normally don't have the kernel sources installed, however for
Gentoo it's quite normal to have kernel sources there.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/python-spidev/python-spidev.hash

@@ -0,0 +1,2 @@
+# Locally calculated
+sha256	355391e9ad3024950590626b080324394c12e75bb21923dbd56a978a1eac6ac7	spidev-3.1.tar.gz

package/python-spidev/python-spidev.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-PYTHON_SPIDEV_VERSION = 3.0
+PYTHON_SPIDEV_VERSION = 3.1
 PYTHON_SPIDEV_SOURCE = spidev-$(PYTHON_SPIDEV_VERSION).tar.gz
 PYTHON_SPIDEV_SITE = https://pypi.python.org/packages/source/s/spidev
 PYTHON_SPIDEV_SETUP_TYPE = distutils