swtpm_setup: Initialize pubek_len (Coverity)

Initialize pubek_len even though it isn't necessary to do so since
it will be initialized in the first function to which it is passed.
However, Coverity complains about pubek_len passed to print_as_hex()
not being initialized, even though this is not possible.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
diff --git a/src/swtpm_setup/swtpm_setup.c b/src/swtpm_setup/swtpm_setup.c
index 49bbaac..020506c 100644
--- a/src/swtpm_setup/swtpm_setup.c
+++ b/src/swtpm_setup/swtpm_setup.c
@@ -662,7 +662,7 @@
     struct swtpm12 *swtpm12;
     struct swtpm *swtpm;
     g_autofree gchar *pubek = NULL;
-    size_t pubek_len;
+    size_t pubek_len = 0;
     int ret = 1;
 
     swtpm12 = swtpm12_new(swtpm_prg_l, tpm_state_path, swtpm_keyopt, gl_LOGFILE,