selftests/kexec: Add missing '=y' to config options

so the file can be used as kernel config snippet.
Signed-off-by: Petr Vorel <pvorel@suse.cz>
[zohar@linux.ibm.com: remove CONFIG_KEXEC_VERIFY_SIG from config]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/kexec/config

-CONFIG_IMA_APPRAISE
-CONFIG_IMA_ARCH_POLICY
-CONFIG_SECURITYFS
-CONFIG_KEXEC_VERIFY_SIG
+CONFIG_IMA_APPRAISE=y
+CONFIG_IMA_ARCH_POLICY=y
+CONFIG_SECURITYFS=y