package/davfs2: bump to version 1.6.0

package/davfs2: bump to version 1.6.0

This bump is needed to fix a build failure with gcc 10:
https://savannah.nongnu.org/support/?func=detailitem&item_id=110186#options

Here is an extract of the bug report:

"It is not a bug to have variables with the same name in different source
files. The bug was the missing keyword "static".

But there was a different bug that was not tolerated by GCC 10. It was
same strange data type conversions in dav_coda.c. The resolution was to
drop coda altogether because there is still fuse which is better suited
anyway.

The new release 1.6.0 should fix all these problems. Please tell me if
there are still problems with GCC 10."

Also update indentation in hash file (two spaces)

Fixes:
 - http://autobuild.buildroot.org/results/42beafade6fd31927c8db14bc52110c0fc5b17c2

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>