integrity: Small code improvements

These changes are too small to warrant their own patches:

The keyid and sig_size members of struct signature_v2_hdr are in BE format,
so use a type that makes this assumption explicit. Also, use beXX_to_cpu
instead of __beXX_to_cpu to read them.

Change integrity_kernel_read to take a void * buffer instead of char *
buffer, so that callers don't have to use a cast if they provide a buffer
that isn't a char *.

Add missing #endif comment in ima.h pointing out which macro it refers to.

Add missing fall through comment in ima_appraise.c.

Constify mask_tokens and func_tokens arrays.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/ima/ima_appraise.c

@@ -240,6 +240,7 @@ int ima_appraise_measurement(enum ima_hooks func,
 	case IMA_XATTR_DIGEST_NG:
 		/* first byte contains algorithm id */
 		hash_start = 1;
+		/* fall through */
 	case IMA_XATTR_DIGEST:
 		if (iint->flags & IMA_DIGSIG_REQUIRED) {
 			cause = "IMA-signature-required";