ima: fix error handling logic when file measurement failed

ima: fix error handling logic when file measurement failed

commit 6dc387d52eb67f45d68caa263704fa4e39ef8e76 upstream.

Restore the error handling logic so that when file measurement fails,
the respective iint entry is not left with the digest data being
populated with zeroes.

Fixes: 54f03916fb89 ("ima: permit fsverity's file digests in the IMA measurement list")
Cc: stable@vger.kernel.org	# 5.19
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>