LU-12561 kernel: Remove 2.6 based SLES11 support

LU-12561 kernel: Remove 2.6 based SLES11 support

2.6 based SLES11 (SLES11SP{0,1,2}) is no longer supported
(and does not build) so remove the series & target for it.

3.x based SLES11 (SP{3,4}) is still supported, and this
should not affect those.

Test-Parameters: trivial

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Ie73c39d24bad26e696a66e907c161348ab4afad5
Reviewed-on: https://review.whamcloud.com/35546
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>