gnu: wpa-supplicant: Update to 2.6.

* gnu/packages/admin.scm (wpa-supplicant-minimal)[source]: Update to
  2.6. Remove 'patches' field.
* gnu/packages/patches/wpa-supplicant-CVE-2015-5310.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2015-5314.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2015-5315.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2015-5316.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2016-4476.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2016-4477-pt1.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2016-4477-pt2.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2016-4477-pt3.patch,
  gnu/packages/patches/wpa-supplicant-CVE-2016-4477-pt4.patch: Delete
  files.
* gnu/local.mk (dist_patch_DATA): Remove them.

Signed-off-by: Leo Famulari <leo@famulari.name>