ima: Fix memory leak in __ima_inode_hash()

In the Linux kernel, the following vulnerability has been resolved: ima: Fix memory leak in __ima_inode_hash() Commit f3cc6b25dcc5 ("ima: always measure and audit files in policy") lets measurement or audit happen even if the file digest cannot be calculated. As a result, iint->ima_hash could have been allocated despite ima_collect_measurement() returning an error. Since ima_hash belongs to a temporary inode metadata structure, declared at the beginning of __ima_inode_hash(), just add a kfree() call if ima_collect_measurement() returns an error different from -ENOMEM (in that case, ima_hash should not have been allocated).