parse_channelstring(): remove useless checks of g_strsplit() results.

1. !names[0] could only be true if tokens[i] is an empty string,
   but we already checked at the beginning of the for() loop that
   this is not the case.

   "(names[1] && names[2])" can also never be true, as
   g_strsplit(x, 2) returns a NULL-terminated pointer array with
   either one or a maximum of two non-NULL strings, so either
   names[1] or names[2] is always == NULL.

   Worst of all, in the case that the separator character "="
   doesn't exist in the string, names[0] is the complete string,
   names[1] is == NULL and names[2] is undefined, so it's an error
   to even access it. (Current glib 2.64.1 seems to return an
   array with at least 3 allocated entries even if the result is
   only one string, but I can't find anything about that in the
   docs so better not rely on this behaviour).

2. Likewise, !range[0] could only be true if names[0] is an empty
   string. But we already asserted that it contains at least a dash
   character.

   So both range[0] and range[1] at least contain pointers to
   empty strings. g_strsplit(x, 2) returns a NULL-terminated
   pointer array with a maximum of (and in this case, exactly)
   two non-NULL strings, which means range[2] is always == NULL.

   As a result, "!range[0] || !range[1] || range[2]" can never be
   true.

parsers.c

@@ -68,13 +68,6 @@ GSList *parse_channelstring(struct sr_dev_inst *sdi, const char *channelstring)
 		}
 
 		names = g_strsplit(tokens[i], "=", 2);
-		if (!names[0] || (names[1] && names[2])) {
-			/* Need one or two arguments. */
-			g_critical("Invalid channel '%s'.", tokens[i]);
-			g_strfreev(names);
-			ret = SR_ERR;
-			break;
-		}
 
 		/* Check first if a channel with the given name already exists, as it
 		 * might contain a dash from a rename in an earlier option.
@@ -102,12 +95,6 @@ GSList *parse_channelstring(struct sr_dev_inst *sdi, const char *channelstring)
 			}
 
 			range = g_strsplit(names[0], "-", 2);
-			if (!range[0] || !range[1] || range[2]) {
-				/* Need exactly two arguments. */
-				g_critical("Invalid channel syntax '%s'.", tokens[i]);
-				ret = SR_ERR;
-				goto range_fail;
-			}
 
 			/* Find start of numeric range (first digit) in range string. */
 			for (sptr = names[0]; *sptr != '-' && !isdigit(*sptr); sptr++);