datapath: compat: Fix static key backport

datapath: compat: Fix static key backport

The original static key backport is based on the upstream
net-next commit 11276d5306b8
("locking/static_keys: Add a new static_key interface").

However, in Canonical's Trusty kernel, it introduced partial static
support which have different definition of some of the macros that
breaks the compatibility code.

For example, in net-next git tree commit 11276d5306b8
("locking/static_keys: Add a new static_key interface").
+ #define DEFINE_STATIC_KEY_TRUE(name)   \
+       struct static_key_true name = STATIC_KEY_TRUE_INIT

On the other hand, in Canonical's Trusty git tree commit 13f5d5d1cccb6
("x86/KVM/VMX: Add module argument for L1TF mitigation")
+ #define DEFINE_STATIC_KEY_TRUE(name)   \
+       struct static_key name = STATIC_KEY_INIT_TRUE

This commit resolves the ovs kernel module compatibility issue on
Trusty kernel.

VMware-BZ: #2251101
Fixes: 6660a9597a49 ("datapath: compat: Introduce static key support")
Tested-by: Greg Rose <gvrose8192@gmail.com>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>