security/smack/: fix misspellings using codespell tool

A typo is found out by codespell tool in 383th line of smackfs.c:

$ codespell ./security/smack/
./smackfs.c:383: numer  ==> number

Fix a typo found by codespell.
Signed-off-by: Xiong Zhenwu <xiong.zhenwu@zte.com.cn>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

security/smack/smackfs.c

@@ -380,7 +380,7 @@ static int smk_parse_rule(const char *data, struct smack_parsed_rule *rule,
  * @data: string to be parsed, null terminated
  * @rule: Will be filled with Smack parsed rule
  * @import: if non-zero, import labels
- * @tokens: numer of substrings expected in data
+ * @tokens: number of substrings expected in data
  *
  * Returns number of processed bytes on success, -ERRNO on failure.
  */