testsdk: Drop lockfile usage

We should be able to test sdks in parallel. As far as I can tell, this
restriction crept in for no good reason, based on locks that testimage used
for the non-qemu case.

Therefore remove the lock and allow sdks to test in parallel.

(From OE-Core rev: 54477664dc13c6aa15b3246f328b66591a340659)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/testsdk.bbclass

@@ -14,8 +14,6 @@
 #
 # where "<image-name>" is an image like core-image-sato.
 
-TESTSDKLOCK = "${TMPDIR}/testsdk.lock"
-
 def testsdk_main(d):
     import os
     import subprocess
@@ -194,4 +192,4 @@ python do_testsdkext() {
 }
 addtask testsdkext
 do_testsdkext[nostamp] = "1"
-do_testsdkext[lockfiles] += "${TESTSDKEXTLOCK}"
+