RedHat: Avoid the DKMS escaping silliness

RedHat: Avoid the DKMS escaping silliness

Depending on the version of DKMS, the current MAKE[0] variable in the
dkms.conf needs different numbers of backslashes. Commit 81a9a33e
tried to address this by changing the contents of dkms.conf depending
on whether or not we were on Fedora. However, the change occurred in
DKMS 2.2, so if someone running RHEL tries to use a newer DKMS, this
will fail.

So instead of trying to guess at the level of escaping we need, just
avoid needing to escape anything with backslashes. We can quote the
heredoc marker to avoid variable expansion inside the heredoc, we can
use a case statement instead of using backticks and local variables
and such, and we can use single quotes for the outer MAKE assignment.
With this, we should not need any backslashes when writing dkms.conf,
so we should work with any DKMS version.

Reviewed-on: http://gerrit.openafs.org/8156
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 72f1f345ece09b1fbd113af17c9e8e25ec9dffa5)

Change-Id: Icbaa1fde7ea222b639a7e5a740f6b18a4a87c74a
Reviewed-on: http://gerrit.openafs.org/8172
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>