tools/cgxset: check for delimiter in name_value string

tools/cgxset: check for delimiter in name_value string

While parsing -r option for name, and value pairs, we rely on strtok()
to return NULL, when there is no delimiter and lhf/rhf can't be mapped
into the name, and value tokens. This assumption is not true, strtok()
returns the whole string when it doesn't find the delimiter. Operating
under this assumption also segfaults later in the code.  Fix it, by
checking for the presence of a delimiter in the passed name_value_str
in parse_r_flag().  This also initializes the pointer to NULL, to avoid
reading them before assignment in the error path.

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>