Fix incorrect usage of sizeof() in res_crypto.

In this case, just remove the memset().  There was a redundant memset that is
done correctly just 2 lines later.
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Merged revisions 359110 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 359114 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@359115 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_crypto.c

@@ -116,7 +116,6 @@ static int pw_cb(char *buf, int size, int rwflag, void *userdata)
 		key->infd = -2;
 		return -1;
 	}
-	memset(buf, 0, sizeof(buf));
 	tmp = ast_hide_password(key->infd);
 	memset(buf, 0, size);
 	res = read(key->infd, buf, size);