gnu: Replace usages of sane-backends with sane.

Replacement done using:
find gnu/packages -name '*.scm' -print0 | xargs -0 sed -ri \
  -e 's/"sane-backends" ,sane-backends/"sane" ,sane/' \
  -e 's/(list[^"]+sane)-backends/\1/' \
  -e 's/^( +sane)-backends/\1/'

* gnu/packages/hardware.scm (hw-probe)[inputs]:
* gnu/packages/wine.scm (wine)[inputs]:
* gnu/packages/python-xyz.scm (python-sane)[inputs]:
* gnu/packages/ocr.scm (gimagereader)[inputs]:
* gnu/packages/libreoffice.scm (libreoffice)[inputs]:
* gnu/packages/kde.scm (ksanecore)[inputs]:
* gnu/packages/gnome.scm (simple-scan, ocrfeeder, colord)[inputs]:
* gnu/packages/scanner.scm (scanbd, xsane, sane-airscan)[inputs]:
Replace sane-backends with sane.

Change-Id: If995e846ed4f53a740119b362e07c36c90a621cb

gnu/packages/hardware.scm

@@ -476,7 +476,7 @@ sharing.")
            procps
            psmisc                       ;for pstree
            rpm
-           sane-backends
+           sane
            smartmontools
            sysstat
            upower